Delaying taskbar loading until user setup completed

> Also keeping it stashed while all-set activity is visible
> Creating a shared state (simiar to saved instance state) for taskbar
> Keeping taskbar stashed while all-set activity is visible

Bug: 194786060
Bug: 201782272
Test: Manual
Change-Id: Iab5e082243a206772266aece62d3028f5acb6400