Rewrite scrim clip modifier

This uses Offscreen composition to have more performant draw phase.

Test: manual, scrim works
Test: performance suites show some improvement
Test: perfetto trace shows significantly shorter draw times during
animation
Flag: com.android.systemui.qs_ui_refactor_compose_fragment
Bug: 383085298

Change-Id: I3ca543ae166dace56ac0e240e6d6a5a06e09fde9