Introduce isMultipleDesktopFrontendEnabledOnDisplay

Only show the frontend UI on the display if it is supported.

Bug: 415367809
Test: Tested desktop mode is disabled in the pixel 9 but enabled
      in the connected display
Flag: com.android.window.flags.enable_multiple_desktops_frontend
Flag: com.android.window.flags.enable_multiple_desktops_backend
Change-Id: Ice376b7a84deb44ef8723efb2277083c7ca97600