[wm]: Make the navigation bar in translucent mode when overlapping with freeform

If you move a freeform window to the navigation bar, there was no response. So If
the freeform window overlaps with the navigation bar area to show that it overlaps,
set the navigation bar display in translucent mode.

Test: Manual - Move a freeform window to the navigation bar
Test: atest WmTests:DisplayPolicyTests
Bug: 129522556
Change-Id: I74df3bb499f9c946593c2aad4bbcf33587413bc9
(cherry picked from commit df95599de4792dd5381f8d4a663eb6060fb237bc)