Intl 2021 Updates (#45647)

* Import of Intl.Locale from #39664

* Handle updating es2020.intl and add es2021 for new DateTimeFormatOptions options - re: #39664

* Extends DateTimeFormatOptions for new Intl APIs - re: #45420

* Handle migrating Intl.NumberFormat.formatToParts to es2018 (keeping esnext.intl around)

* Adds Intl.DisplayNames to es2020 - re: #44022

* Remove attributes added in es2021 from es2020 - re: #42944

* Add a reference to es2021 in the command line parser

* Adds some docs about the lib files

* Baselines

* Allow undefined in Intl inputs to allow for ergonomic usage of exactOptionalPropertyTypes - see #45652

* Adds some tests covering the APIs

* Apply suggestions from code review

Co-authored-by: Nathan Shively-Sanders <293473+sandersn@users.noreply.github.com>

* Handle PR feedback

* More review improvements

Co-authored-by: Nathan Shively-Sanders <293473+sandersn@users.noreply.github.com>

src/compiler/commandLineParser.ts

@@ -71,6 +71,7 @@ namespace ts {
         ["es2021.promise", "lib.es2021.promise.d.ts"],
         ["es2021.string", "lib.es2021.string.d.ts"],
         ["es2021.weakref", "lib.es2021.weakref.d.ts"],
+        ["es2021.intl", "lib.es2021.intl.d.ts"],
         ["esnext.array", "lib.es2019.array.d.ts"],
         ["esnext.symbol", "lib.es2019.symbol.d.ts"],
         ["esnext.asynciterable", "lib.es2018.asynciterable.d.ts"],