Make shared ManageWindowsViewContainer more generic

This change adapts the container that both Launcher and Shell share to
allow the Launcher side to pass in bitmaps instead of TaskSnapshot which
Launcher doesn't have access to.

Bug: 315989246
Test: Manual
Flag: com.android.launcher3.enable_multi_instance_menu_taskbar
Change-Id: I15a733dff7302c010858d40b8be2978da6748b0c