Change resolution via synthetic mode.

This is a fake resolution change where resolution is changed in LogicalDisplay and SurfaceFlinger doesn't know about it.

Bug: 438485020
Flag: com.android.server.display.feature.flags.enable_size_override_for_external_displays
Test: atest LogicalDisplayTest
Change-Id: I9c45056268f8d6075e26c6cbb265ee6a69d477ea