Start an activity cross profile in same task.

Adding new overloaded methods of startMainActivity and startActivity that allow the caller to
specify that the new activity should be added to the current task rather
than creating a new one.
Test: atest android.devicepolicy.cts.CrossProfileAppsTest FrameworksServicesTests:com.android.server.pm.CrossProfileAppsServiceImplTest
Bug: 215425075

Change-Id: I21c258c5962daefb32f65779035f4ba8f0474da7