Address new activity control API feedback

 - replace @UserId int with @NonNull UserHandle in the new
   onActivityLaunchBlocked callback
 - rename the new policy POLICY_TYPE_BLOCKED_ACTIVITY_BEHAVIOR to
   POLICY_TYPE_BLOCKED_ACTIVITY

Fix: 357686109
Test: presubmit, CTS
Flag: android.companion.virtualdevice.flags.activity_control_api
Change-Id: I7086d4c09b691d9047541b370c696fd8c5206d5c