autoclick: Hide panel when mouse disconnects

Observe pointing device (mouse) connection state.

- Hide autoclick type panel and scroll panel when all pointingn devices
are disconnected.
- Show type panel when next time a pointing device is connected.

Demo: http://b/422538372#comment8

Change-Id: I84a631e1c878ae24105646927b4ef2b69067fa50
Bug: b/422538372
Test: AutoclickControllerTest
Flag: com.android.server.accessibility.enable_autoclick_indicator