Add support for taskbar background to wrap around hotseat

Currently only enabled for app launch animation

Future work is planned:
- Overview to home
- App dismiss
- When QSB is drawn inline

Bug: 345768019
Test: Launch an app, taskbar background and stashed handle will
      first wrap around hotseat before transforming into the
      stashed handle.
      Verified by locally forcing taskbar background and
      stashed handle to always draw.
Flag: com.android.launcher3.enable_scaling_reveal_home_animation
Change-Id: I9ab1870f87247b6a1b53a352ac3eb0183b7a1a1d