Added restriction for switching to Headless SYSTEM user.

On HSUM(HeadlessSystemUserMode) user 0 will not be a Full user and is
not going to run in foreground.
Added restrictions to prevent switching to non-full user
which will eventually restrict switching to user 0 in headless.

In some form factors we do need to switch to headless SYSTEM user even when its not FULL like in AUTO, added overlay property to allow switching to non-full SYSTEM user in case the property is enabled.

Refactor and Deprecated UserInfo.supportsSwitchToByUser by UserInfo.supportsSwitchTo after adding the restrictions to prevent switch to non-full users.

Removed redundant userInfo.isProfile check from UserController.switchUser.

Test: m , atest ActivityManagerTest -c
Bug: 262402637
Change-Id: I871e6721ce6745d5a9e3009162e3d6ac8a284908