Allow auto-fill services to disable themselves

1. Added a new API for a connected auto-fill service to
   disable itself

2. Added a new shell command to destroy all pending sessions
   which is used in CTS tests

3. Fixed a bug where the unbind timeout was in minutes
   instead of seconds

Test: wrote CTS tests, all auto-fill tests pass

bug:35848030

Change-Id: I681605aa0b8c004a0f14e30b57117c291d89a894