Introduce UserProperties class

Introduces a UserProperties class, which holds (potentially dynamic)
information about each user, where the (default) values depend on the
user type.
This can usually be used instead of
isManagedProfile() calls, giving fine-grained information, rather than
course-grained queries about the user type.

The system copies this object before delivering it to any callers,
filtering the properties by the permissions held by the caller.

The object can be parsed from XML, which is used for both persisting a
user's properties to disk, as well as for reading in the default
properties for each user type.

Bug: 235065648
Bug: 237399048
Bug: 170249807
Bug: 234439331

Test: atest UserManagerServiceUserPropertiesTest
Test: atest android.multiuser.cts.UserManagerTest
Test: atest com.android.server.pm.UserManagerTest
Test: atest UserManagerServiceUserTypeTest

Change-Id: If37480abafa784ce197b482103b6537a60fe2653