Mock InputEventReceiver for clipboard tests

Some inputEventReceiver.dispose() calls in tests go through animators, and were still getting called on a thread that didn't evaluate to equal with the main thread. This change pulls the InputMonitor and InputEventReceiver into an injected provider.

Bug: 412412622
Fix: 412412622
Test: atest ClipboardOverlayControllerTest (after adding the change that
crashes if calls don't happen on the main thread; see bug for details)
Flag: EXEMPT minor bugfix

Change-Id: I9385f7856d78cf2ba4ee2d686674bf06d4ebfa9b