Key input consumers by token and not by name

- Currently input consumers are singletons keyed by static name, which
  is problematic because the per-user Launcher process registers and
  unregisters the input consumer when SysUI binds to the current user's
  TouchInteractionService.  However, the ordering of service create
  and destroy when switching users is not guaranteed, so you can end up
  with user 2's service being created before user 1's service destroy is
  called.  Currently this crashes because we expect singletons.
- This change changes the tracking of input consumers to be by token
  (which is already passed by the caller), and uses the token for
  identifying the input consumer to destroy.

  In addition, it only enforces a singleton check for input consumers
  registered for the same user.  And when fetching an input consumer by
  name, the last registered consumer with that name takes precedence and
  is returned.  This allows multiple Launcher processes to register
  a consumer for the current user without preventing the closing Launcher
  service from removing its previously registered consumer.

Fixes: 300973954
Test: Verify with multiple users that there's no race between registering
      and destroying the recents input consumer



Change-Id: I64d2453c3671747b5799f26b628448fdf03bdb77