ICU-22557 Add kxv_IN to build-icu-data.xml, update generated stub data files

[pedberg-icu]

Checklist

• Required: Issue filed: https://unicode-org.atlassian.net/browse/ICU-22557
• Required: The PR title must be prefixed with a JIRA Issue number.
• Required: The PR description must include the link to the Jira Issue, for example by completing the URL in the first checklist item
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• Issue accepted (done by Technical Committee after discussion)
• Tests included, if applicable
• API docs and/or User Guide docs changed or added, if applicable

Fix the missing stub data files (in data subtrees other than locales such as curr, lang, region) for kxv_Latn and kxv_Latn_IN, and also add alias files for kxv_IN; just needed to add kxv_IN to the locales list in tools/cldr/cldr-to-icu/build-icu-data.xml (since it is actually an alias locale - to kxv_Latn_IN - and all of the stubs get filled in for such aliases and their targets etc.).