Adding user property for CrossProfileContentSharingStrategy.

This property would be used by clients like Sharesheet, DocsUi, etc
to determine how content sharing permissions can be applied to
inter-profile operations, such as sharing Photos, Documents, Media, etc.

Using this, profiles can setup delegated users for content sharing,
originating from that profile. For ex, Private Profile can say that
Cross Profile content sharing to/from it, should be deemed as if it
was originating to/from its parent.

When not sert, the profile itself should be taken as the delegated user
for hanndling cross-profil sharing.

Bug: 307515481
API-Coverage-Bug: 314094348
Test: atest UserManagerServiceUserPropertiesTest
Test: atest UserManagerServiceUserTypeTest
Test: atest FrameworksServicesTests:UserManagerTest
Change-Id: I706ce9bbc7d53c7b734d36a0deb4556c854a5190