Add and update log statements for desktop proto

Add and update log statements in DesktopTasksController to include the
controller name in log string. Simplifies tracking down the messages.
Add log statements to DesktopModeTaskRepository to ease debugging.

Bug: 280657549
Test: build wmshell
Change-Id: I37579eba3b0a8b6883f2f2b745061028b42db369