Add IME tracing to data gathered in WinscopeTrace

This change starts and stops IME tracing together with the other traces
gathered when the WinscopeTrace tile is used. The data is saved along
the other traces in /data/misc/wmtrace/.

Bug: 154348613
Bug: 167948910
Test: flash a device together with the other change in this topic
      enable the WinscopeTrace tile and do some actions
      disable the WinscopeTrace tile
      do a bugreport and visualise contents in Winscope
      or just check contents of /data/misc/wmtrace/ through adb
Change-Id: If0b16dd5c19aa8bb33174abe2fe242fc8e6bdd90