Handle multiple touchpads in TouchpadDebugViewController

Add logic to the TouchpadDebugViewController to be able to handle,
multiple touchpad connection/disconnection, to avoid a state of
having a touchpad connected but no View after original touchpad
disconnection.
Made sure that the View's colour only changes when a
HardwareProperty of the same ID is received.

Bug: 363979581

Test: Updated unit tests to test sending HardwareProperties with
different deviceIds to the view and verify that only the one with
the same deviceId affected the View.
Manual testing by connecting multiple touchpads and verifying the
result of disconnecting the first or second touchpad and making
sure we get the desired behaviour.
Flag: com.android.hardware.input.touchpad_visualizer

Change-Id: I9dc8c53ed48e53002d9f13bed250d1a65ddbf20a