Taskbar All Apps button visual updates

- Moved to new position
- Using 3x3 icon
- New Colors

Checked with visd that this half is good to go,
will follow up with positioning of the 3x3 icon within
its container.

Bug: 259712417
Test: manual, LTR/RTL modes, transient/persisent models

Change-Id: I298b6dbca004cdb8920e6533fffc8ca83e0197f9