WorkManager OOM

This project demonstrates how the GreedyScheduler.mConstrainedWorkSpecs can grow unbounded, as well as SerialExecutor.mTasks due to worker constraints. In degenerate cases, this can cause OOM errors. Filed at https://issuetracker.google.com/issues/235259756

Repro

• Put your emulator/device into airplane mode
• Repeatedly launch and background the app
• Place breakpoints in GreedyScheduler.schedule (L156 in WorkManager v2.7.1) and see how mConstrainedWorkSpecs grows unbounded.
• You can also place a breakpoint in SerialExecutor.execute to see that its mTasks Array grows unbounded as well. When mTasks runs out of room, it doubles in size.
• Since WorkManager keeps it unexecuted tasks in a db, killing and restarting the app does not fix the issue.