Display Enable power ON

When enabling an external display
in the default power group, it
doesn't always power ON.

To fix this there is a need to call
applyDisplayChangedLocked
which would propagate information
about isEnabled change to DPC.

Change-Id: Ia8a9c177f745dc15bb06cdc712d40d59fd3cbf63
Bug: 368131655
Test: atest DisplayManagerServiceTest
Flag: com.android.server.display.feature.flags.enable_apply_display_changed_during_display_added