Add Support For Built-in Kotlin (flutter#184227)

We add support for Built-in Kotlin by applying KGP when missing. When
flutter android builds are invoked and KGP is applied, an appropriate
migration message will be logged. Builds will still break when Built-in
Kotlin is the default (AGP >= 9) until we set the default to the legacy
behavior (applying KGP).

Fixes flutter#183909
Related to flutter#181557

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Fixes] where supported.
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Author: jesswrd