Various minor cleanups and improvements to the project

[tresat]

Copy IntelliJ code style rules from gradle/gradle

• Update git ignore to allow these files to be tracked in repo.

Remove default SDK versions from Android plugin

• These can be supported by conventions now. This adds conventions for SDK versions to the example Android builds in the unified-prototype. Also restores the rootProject.name, which is now supported.

Remove unnecessary declarative annotations

• These annotations are more appropriately present on the child types.

Use DependencyCollector to add deps for Compose

[tresat]

Please ignore the failing action - it's due to missing Swift.