Enable overriding density for desktop tasks

Add a new API to WindowContainerTransaction to support updating the
container density.
This allows us to update the configuration object with a new density
value that would get applied by the WindowOrganizerController.
Allow list density changes in WindowOrganizerController as an allowed
configuration change.
Update DesktopTasksController to change the density value when moving a
task to desktop or back to fullscreen (if enabled).
Use system property persist.wm.desktop_mode_density to override the
density for desktop tasks. Allowed range for the density override is 100
to 1000.

Bug: 272529050
Test: atest DesktopTasksControllerTest
Change-Id: I96539176252fdd5b69b02e3bd1b6a4231990decb