[CD][Alt+Tab] Implement skeleton code for KQS on CD

- This change will not render KQS on connected display (CD) even with the flag ON as taskbars are not yet created for connected displays.

Bug: 382762871
Change-Id: Id59fb23630aaf0e74c35818f2a4ca56e5ef2e7bb
Flag: com.android.launcher3.enable_alt_tab_kqs_on_connected_displays
Test: manually built and run the CUJ