Implement Font Scaling Quick Settings Tile (3/n)

Setup the basic layout of the dialog that would show up after clicking
the font scaling tile. The dialog includes the Title, the Done button,
and a seekbar which allows users to change the font size.

Bug: 242326166
Test: Attach a video to the bug
Test: atest FontScalingTileTest
Change-Id: I53db74af00e358a5e35283128a11164d4ae6733e