[WIP] AGP 9 Ecosystem Playground

[jesswrd]

This PR contains auditing work for AGP 9 for plugins. The objective is to identify the changes required to build a Flutter app with plugins on Android AGP 9, and to determine which of those configurations maintain backward compatibility with older AGP versions. Ideally, we could identify one set of changes that could succeessfully build on apps on AGP 9 and is also backwards compatible.

The main migration steps required for AGP 9:

1. Using new agp DSL (we can't do this yet due to usage of internal AGP apis. must opt out with android.newDsl=false)
2. Use built-in Kotlin

The first migration step is backwards compatible. Some of the required changes in the second migration step are backwards compatible while others are not. In this approach, the non compatible is made backwards compatible with an if-statement.

Pre-Review Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I read the Tree Hygiene page, which explains my responsibilities.
• I read and followed the relevant style guides and ran the auto-formatter.
• I signed the CLA.
• The title of the PR starts with the name of the package surrounded by square brackets, e.g. [shared_preferences]
• I linked to at least one issue that this PR fixes in the description above.
• I updated pubspec.yaml with an appropriate new version according to the pub versioning philosophy, or I have commented below to indicate which version change exemption this PR falls under¹.
• I updated CHANGELOG.md to add a description of the change, following repository CHANGELOG style, or I have commented below to indicate which CHANGELOG exemption this PR falls under¹.
• I updated/added any relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or I have commented below to indicate which test exemption this PR falls under¹.
• All existing and new tests are passing.

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Footnotes

1. Regular contributors who have demonstrated familiarity with the repository guidelines only need to comment if the PR is not auto-exempted by repo tooling. ↩ ↩² ↩³

[jesswrd]

Flutter apps on Android successfully build on AGP 9 and versions before AGP 9 when using kotlin.compilerOptions{} DSL. This is because the usage of kotlinOptions{} and kotlin.compilerOptions{} DSL is dependent on the KGP version and not the AGP version.

Some context: apparently kotlinOptions{} DSL has been deprecated since KGP 2.0.0 and it is recommended that kotlin.compilerOptions{} DSL be used instead here.

[jesswrd]

Even though android.newDsl=false was introduced in AGP 9, it looks like the android.newDsl can successfully build on versions older than AGP 9.

[fluttergithubbot]

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