Do not specify a Kotlin version in the RN rootProject

[cortinico]

Summary

As we introduced KGP inside ReactAndroid (cc @ShikaSD), we now need to specify a version for it (as users will consume that build on Android New Architecture.

Currently, the version is loaded in the RN rootProject which is not available on user's project. I'm cleaning this up.

Changelog

[Internal] - Do not specify a Kotlin version in the RN rootProject

Test Plan

Tested on a nightly version with

npx react-native init RNNightly --version nightly

[facebook-github-bot]

@cortinico has imported this pull request. If you are a Meta employee, you can view this diff on Phabricator.

[analysis-bot]

Platform	Engine	Arch	Size (bytes)	Diff
ios	-	universal	n/a	--

Base commit: c5babd9
Branch: main

[react-native-bot]

This pull request was successfully merged by @cortinico in bfc3935.

^{When will my fix make it into a release? | Upcoming Releases}