Create a new user restriction to disallow user switching

For multi-user session implementation, we want to block the user from
going back to user 0. Therefore, we block the user switcher in the
secondary user, as well as swtiching via user section in Settings app.

Bug: 64382189
Test: Manually verify user switcher is not displayed in QuickSettings
Test: Manulaly verify not able to remove or switcher user in user
      section in Setting app
Change-Id: I84bc9e67e3fe7fccb75edf0fc49b775b902f5290