AppSecurityPermissions: add support for revoking permissions

Add UI support for revoking optional permissions. When the user
taps on an optional permission, two new boxes will appear:

  [Cancel] | [Revoke]

Selecting [Revoke] will revoke the permission from the app.

The [Cancel] / [Revoke] options are only shown for apps which support
optional permissions.

Bug: 8332307
Change-Id: I27e374773747737e3a6d7f48ea1448a0178e3393