Fix broken recents view loading with overview in window enabled

If recents view is not attached to window when applyLoadPlan is called, then the taskviews will never update until mTaskListChangeId is invalidated. This mainly affects RecentsWindowManager, so added a callback to only initialize after recents view has attached to window.

Flag: com.android.launcher3.enable_launcher_overview_in_window
Bug: 377678992
Test: pre/post-submit tests; opened overview several times
Change-Id: Ie430fb5b0b2b6870c12fed1c6a394088cad1ac17
3 files changed