This PR are mostly Normative but have some editorial parts

1. Editorial: Add text to explain ComputedRoundingPriority in section
"15.4 Properties of Intl.NumberFormat Instances"
https://tc39.es/ecma402/#sec-properties-of-intl-numberformat-instances
and
"16.4 Properties of Intl.PluralRules Instances
https://tc39.es/ecma402/#sec-properties-of-intl-pluralrules-instances

2. Editorial: Add ComputedRoundingPriority to Intl.PluralRules
https://tc39.es/ecma402/#sec-intl.pluralrules
Without this, the spec is not implementable because InitializePluralRules
call "SetNumberFormatDigitOptions(pluralRules, options, +0𝔽, 3𝔽, "standard")."
and SetNumberFormatDigitOptions assume the intlObj has `[[ComputedRoundingPriority]]`

3. Normative: Move the reading of "roundingPriority" from before reading
   "roundingIncrement" to after reading "roundingMode" so these three
   fields are read in alphabetic order.
https://tc39.es/ecma402/#sec-setnfdigitoptions

4. Normative: Move the output order of "roundingIncrement" from after
   output "roundingMode" to before that so these two
   fields are read in alphabetic order in the resolvedOptions of both
   Intl.NumberFormat and Intl.PluralRules.
   https://tc39.es/ecma402/#sec-intl.numberformat.prototype.resolvedoptions
   https://tc39.es/ecma402/#sec-intl.pluralrules.prototype.resolvedoptions

5. Normative: Move the output of "roundingPriority" from after
   "trailingZeroDisplay" before that to sync w/ Intl.NumberFormat after
   PR768.
   https://tc39.es/ecma402/#sec-intl.pluralrules.prototype.resolvedoptions

6. Normative: Move the output of "pluralCategories" from after
   "trailingZeroDisplay" to before "roundingIncrement" so these options
   will be in alphabetic order.
   https://tc39.es/ecma402/#sec-intl.pluralrules.prototype.resolvedoptions