Add new LeakCanary Plumber library

[pyricau]

This would be essentially the mirror of AndroidExcludedRef, a production library that uses various hacks to clean up framework leaks.

[pyricau]

cc @bishiboosh who mentioned that idea

[pyricau]

Some leaks have clear triggers on when to try and fix them, while others less so and we've typically used a timer based approach in the past.

I'm thinking instead we could on top of LeakSentry and attempt clearing things when LeakSentry lets us know there are leaking instances. That likely means having an intermediate report step where the sniper snoops in and reports and LeakCanary does not immediately dump / retries later.

[pyricau]

The viewgroup leak in P is definitely worth looking at fixing: #1081 (comment)

[pyricau]

Other option: https://twitter.com/ianhlake/status/1146793902336139264

[pyricau]

Note: I went with the timer based approach rather than relying on signals from the app watcher because that way we don't have a direct dependency on it.