Introduce LeakWatcherRule to monitor Paparazzi leaks

[jrodbx]

POC to help figure out situations like Compose Runtime leaks.

To run, ./gradlew paparazzi-gradle-plugin:test --tests=app.cash.paparazzi.gradle.PaparazziPluginTest.compose

in conjunction with modifications to either:

• Paparazzi#forceReleaseComposeReferenceLeaks (to test potential fixes to Compose runtime leaks!)
• paparazzi-gradle-plugin/src/test/projects/compose/src/test/java/app/cash/paparazzi/plugin/test/ComposeTest.kt (to try new Composables which may surface other leaks!)

[pyricau]

Love it

[geoff-powell]

Nice 👍🏽