Add MTE Settings.

MTE is a technology to help prevent exploitation of some security bugs.
We want to offer users that want to trade off a slight reduction in
performance for higher security the option to do so from the settings
menu.

Test: make RunSettingsRoboTests
      check UI manually
Bug: 245624194
Change-Id: Ifbb76e124142ae843ce90bd604ae8417d65fcc7b