Fix CTS flakes caused by creating duplicated inputconsumer

The nav InputConsumer would be used while nav bar is hidden and
would pending to be dismissed when nav bar isn't visible. That ensure
the application doesn't see the event when nav bar is coming back.

Some CTS flakes from window manager crashing that caused by
creating duplicated inputconsumer exception. The reason is the
previous one hadn't been disposed yet.

- Seperate dismiss and dispose that could make sure that the previous
  nav consumer is removed from InputMonitor when creating the new one,
  and its input receiver will be disposed on the attached thread.

Test: atest com.android.server.wm
Test: atest CtsUiRenderingTestCases
Bug: 148395441
Change-Id: I03c2f3aaece4f3f000651b18709e0732d5965604