Update SELinux Policy for bufferhubd

Create a new service type buffer_hub_binder_service for
BufferHubBinderService and allow bufferhubd to publish the service.

Add the service to 26.0, 27.0 and 28.0 compat ignore files since the
service is not available in past versions.

Fixes: 116022258
Test: build passed

Change-Id: I5a21f00329ed474433d96c8d1ce32377f20cada3
diff --git a/private/service_contexts b/private/service_contexts
index ebd8a36..e04227b 100644
--- a/private/service_contexts
+++ b/private/service_contexts
@@ -22,6 +22,7 @@
 bluetooth_manager                         u:object_r:bluetooth_manager_service:s0
 bluetooth                                 u:object_r:bluetooth_service:s0
 broadcastradio                            u:object_r:broadcastradio_service:s0
+bufferhubd                                u:object_r:buffer_hub_service:s0
 carrier_config                            u:object_r:radio_service:s0
 clipboard                                 u:object_r:clipboard_service:s0
 com.android.net.IProxyService             u:object_r:IProxyService_service:s0