Deduplicate tz locations against root (#5759)

A lot of location names are the same in many languages. 

For exemplar cities we have root data, however for territories we don't.
For territories I'm resolving the `und` name by using a Latin-script
endonym (i.e. for region `XY`, resolve `und-Latn-XY`), and if that
fails, just use English (not perfect, but it's better than the raw
region code for both display purposes and deduplication).

components/datetime/src/format/neo.rs

@@ -497,6 +497,7 @@ impl From<RawDateTimeNames<DateMarker>> for RawDateTimeNames<DateTimeMarker> {
             weekday_names: other.weekday_names,
             dayperiod_names: DateTimeNamesData2::none(),
             zone_essentials: (),
+            locations_root: (),
             locations: (),
             mz_generic_long: (),
             mz_generic_short: (),
@@ -517,6 +518,7 @@ impl From<RawDateTimeNames<TimeMarker>> for RawDateTimeNames<DateTimeMarker> {
             weekday_names: DateTimeNamesData2::none(),
             dayperiod_names: other.dayperiod_names,
             zone_essentials: (),
+            locations_root: (),
             locations: (),
             mz_generic_long: (),
             mz_generic_short: (),
@@ -545,6 +547,8 @@ pub(crate) struct RawDateTimeNames<R: DateTimeNamesMarker> {
         >,
     zone_essentials:
         <R::ZoneEssentials as DateTimeNamesHolderTrait<tz::EssentialsV1Marker>>::Container<()>,
+    locations_root:
+        <R::ZoneLocations as DateTimeNamesHolderTrait<tz::LocationsV1Marker>>::Container<()>,
     locations: <R::ZoneLocations as DateTimeNamesHolderTrait<tz::LocationsV1Marker>>::Container<()>,
     mz_generic_long:
         <R::ZoneGenericLong as DateTimeNamesHolderTrait<tz::MzGenericLongV1Marker>>::Container<()>,
@@ -589,6 +593,7 @@ pub(crate) struct RawDateTimeNamesBorrowed<'l> {
     weekday_names: OptionalNames<(fields::Weekday, FieldLength), &'l LinearNamesV1<'l>>,
     dayperiod_names: OptionalNames<FieldLength, &'l LinearNamesV1<'l>>,
     zone_essentials: OptionalNames<(), &'l tz::EssentialsV1<'l>>,
+    locations_root: OptionalNames<(), &'l tz::LocationsV1<'l>>,
     locations: OptionalNames<(), &'l tz::LocationsV1<'l>>,
     mz_generic_long: OptionalNames<(), &'l tz::MzGenericV1<'l>>,
     mz_generic_short: OptionalNames<(), &'l tz::MzGenericV1<'l>>,
@@ -1659,6 +1664,7 @@ impl<R: DateTimeNamesMarker> RawDateTimeNames<R> {
             weekday_names: <R::WeekdayNames as DateTimeNamesHolderTrait<WeekdayNamesV1Marker>>::Container::<_>::new_empty(),
             dayperiod_names: <R::DayPeriodNames as DateTimeNamesHolderTrait<DayPeriodNamesV1Marker>>::Container::<_>::new_empty(),
             zone_essentials: <R::ZoneEssentials as DateTimeNamesHolderTrait<tz::EssentialsV1Marker>>::Container::<_>::new_empty(),
+            locations_root: <R::ZoneLocations as DateTimeNamesHolderTrait<tz::LocationsV1Marker>>::Container::<_>::new_empty(),
             locations: <R::ZoneLocations as DateTimeNamesHolderTrait<tz::LocationsV1Marker>>::Container::<_>::new_empty(),
             mz_generic_long: <R::ZoneGenericLong as DateTimeNamesHolderTrait<tz::MzGenericLongV1Marker>>::Container::<_>::new_empty(),
             mz_generic_short: <R::ZoneGenericShort as DateTimeNamesHolderTrait<tz::MzGenericShortV1Marker>>::Container::<_>::new_empty(),
@@ -1677,6 +1683,7 @@ impl<R: DateTimeNamesMarker> RawDateTimeNames<R> {
             weekday_names: self.weekday_names.get().inner,
             dayperiod_names: self.dayperiod_names.get().inner,
             zone_essentials: self.zone_essentials.get().inner,
+            locations_root: self.locations_root.get().inner,
             locations: self.locations.get().inner,
             mz_generic_long: self.mz_generic_long.get().inner,
             mz_generic_short: self.mz_generic_short.get().inner,
@@ -1896,6 +1903,10 @@ impl<R: DateTimeNamesMarker> RawDateTimeNames<R> {
             id: DataIdentifierBorrowed::for_locale(locale),
             ..Default::default()
         };
+        self.locations_root
+            .load_put(provider, Default::default(), variables)
+            .map_err(|e| MaybePayloadError2::into_single_load_error(e, field))?
+            .map_err(SingleLoadError::Data)?;
         self.locations
             .load_put(provider, req, variables)
             .map_err(|e| MaybePayloadError2::into_single_load_error(e, field))?
@@ -2626,6 +2637,7 @@ impl<'data> RawDateTimeNamesBorrowed<'data> {
     pub(crate) fn get_payloads(&self) -> crate::time_zone::TimeZoneDataPayloadsBorrowed<'data> {
         TimeZoneDataPayloadsBorrowed {
             essentials: self.zone_essentials.get_option(),
+            locations_root: self.locations_root.get_option(),
             locations: self.locations.get_option(),
             mz_generic_long: self.mz_generic_long.get_option(),
             mz_generic_short: self.mz_generic_short.get_option(),

components/datetime/src/time_zone.rs

@@ -210,7 +210,9 @@ impl ResolvedNeoTimeZoneSkeleton {
 pub(crate) struct TimeZoneDataPayloadsBorrowed<'a> {
     /// The data that contains meta information about how to display content.
     pub(crate) essentials: Option<&'a provider::time_zones::TimeZoneEssentialsV1<'a>>,
-    /// The location names, e.g. Germany Time
+    /// The root location names, e.g. Toronto
+    pub(crate) locations_root: Option<&'a provider::time_zones::LocationsV1<'a>>,
+    /// The language specific location names, e.g. Italy
     pub(crate) locations: Option<&'a provider::time_zones::LocationsV1<'a>>,
     /// The generic long metazone names, e.g. Pacific Time
     pub(crate) mz_generic_long: Option<&'a provider::time_zones::MetazoneGenericNamesV1<'a>>,
@@ -564,7 +566,15 @@ impl FormatTimeZone for GenericLocationFormat {
             return Ok(Err(FormatTimeZoneError::MissingZoneSymbols));
         };
 
-        let Some(location) = locations.locations.get(&time_zone_id) else {
+        let Some(locations_root) = data_payloads.locations_root else {
+            return Ok(Err(FormatTimeZoneError::MissingZoneSymbols));
+        };
+
+        let Some(location) = locations
+            .locations
+            .get(&time_zone_id)
+            .or_else(|| locations_root.locations.get(&time_zone_id))
+        else {
             return Ok(Err(FormatTimeZoneError::Fallback));
         };
 
@@ -600,8 +610,15 @@ impl FormatTimeZone for SpecificLocationFormat {
         let Some(locations) = data_payloads.locations else {
             return Ok(Err(FormatTimeZoneError::MissingZoneSymbols));
         };
+        let Some(locations_root) = data_payloads.locations_root else {
+            return Ok(Err(FormatTimeZoneError::MissingZoneSymbols));
+        };
 
-        let Some(location) = locations.locations.get(&time_zone_id) else {
+        let Some(location) = locations
+            .locations
+            .get(&time_zone_id)
+            .or_else(|| locations_root.locations.get(&time_zone_id))
+        else {
             return Ok(Err(FormatTimeZoneError::Fallback));
         };
 
@@ -642,6 +659,9 @@ impl FormatTimeZone for GenericPartialLocationFormat {
         let Some(locations) = data_payloads.locations else {
             return Ok(Err(FormatTimeZoneError::MissingZoneSymbols));
         };
+        let Some(locations_root) = data_payloads.locations_root else {
+            return Ok(Err(FormatTimeZoneError::MissingZoneSymbols));
+        };
         let Some(non_locations) = (match self.0 {
             FieldLength::Wide => data_payloads.mz_generic_long.as_ref(),
             _ => data_payloads.mz_generic_short.as_ref(),
@@ -651,7 +671,11 @@ impl FormatTimeZone for GenericPartialLocationFormat {
         let Some(metazone_period) = data_payloads.mz_periods else {
             return Ok(Err(FormatTimeZoneError::MissingZoneSymbols));
         };
-        let Some(location) = locations.locations.get(&time_zone_id) else {
+        let Some(location) = locations
+            .locations
+            .get(&time_zone_id)
+            .or_else(|| locations_root.locations.get(&time_zone_id))
+        else {
             return Ok(Err(FormatTimeZoneError::Fallback));
         };
         let Some(non_location) = non_locations.overrides.get(&time_zone_id).or_else(|| {