Add NotificationRemoteInputManager and associated tests.

This splits out several remote input related pieces of logic:
  1. Handling clicks on remote views
  2. Handling notifications kept for remote input
  3. Handling notifications to be removed on NotificationPresenter
      collapse.

Bug: 63874929
Bug: 62602530
Test: runtest systemui
Test: Compile and run
Change-Id: I7acd4bcb2ab7bde67d307408f509d3ca038eb3d4