Support accessibility shorcut secondary action (2/n)

Create a dialog that could let users choose their preferred accessibility
shortcut.

This CL only contains dialog layout and its utility methods.
Related logic implementation will be added in next CL.

Bug: 142531156
Test: Maunal
Change-Id: I7bfccea96cc47dd213b4d828499c10b290e24330
6 files changed