Split mediaprovider as a separate domain from priv_app

MediaProvider requires permissions that diverge from those
of a typical priv_app. This create a new domain and removes
Mtp related permissions from priv_app.

Bug: 33574909
Test: Connect with MTP, download apps and files, select ringtones
Test: DownloadProvider instrument tests, CtsProviderTestCases

Change-Id: I950dc11f21048c34af639cb3ab81873d2a6730a9
diff --git a/private/seapp_contexts b/private/seapp_contexts
index 4356889..dc7e389 100644
--- a/private/seapp_contexts
+++ b/private/seapp_contexts
@@ -102,6 +102,7 @@
 user=shared_relro domain=shared_relro
 user=shell seinfo=platform domain=shell type=shell_data_file
 user=_isolated domain=isolated_app levelFrom=user
+user=_app seinfo=media domain=mediaprovider name=android.process.media type=app_data_file levelFrom=user
 user=_app seinfo=platform domain=platform_app type=app_data_file levelFrom=user
 user=_app isV2App=true isEphemeralApp=true domain=ephemeral_app type=app_data_file levelFrom=user
 user=_app isV2App=true domain=untrusted_v2_app type=app_data_file levelFrom=user