Taskbar layout update

> Calculating the hotseat padding statically
> Animating taskbar views individually when animating to home
  instead of a layout animation
> Moving all navbar buttons to a separate layout/controller and independent
  of Launcher
> Fixing RTL layout for taskbar and nav bar

Bug: 187353581
Test: Manual
Change-Id: If21696f38beee328f553e467394776a8e8ed4c3e