Add icon to Preference widget

Also,
- Fix SwitchPreference's changeable not updatable
- Use MaterialTheme.colorScheme.onSurfaceVariant as tint color for Footer icon

Bug: 235727273
Test: Manual with Gallery App
Change-Id: Ifcd33a8a9975f70ac0aea8c4869d1aa0e3b34ec2
5 files changed