Make `DesktopModeLaunchParamsModifier` no-op if desktop mode not supported

From now on only attempt to apply desktop mode launch param modifications
if flag is enabled and device is compatible with desktop windowing or has
been overridden to ignore this restriction.

Fixes: 330740314
Test: atest WmTests:DesktopModeLaunchParamsModifierTests
Change-Id: I77c30376c39ee028122d4347e20e54ffb68a1b5a