Add get_auth_token permission to allow credstore to call keystore2.

This CL adds a new keystore2 permission "get_auth_token"and grants this
permission to credstore which needs to call keystore2 to obtain
authtokens.

Bug: 159475191
Test: CtsVerifier
Change-Id: I1c02ea73afa6fe0b12a2d74e51fb4a8a94fd4baf
diff --git a/private/access_vectors b/private/access_vectors
index a02a2a8..1ab4f73 100644
--- a/private/access_vectors
+++ b/private/access_vectors
@@ -718,6 +718,7 @@
 	change_user
 	clear_ns
 	clear_uid
+	get_auth_token
 	get_state
 	list
 	lock
diff --git a/public/credstore.te b/public/credstore.te
index a2376d2..97d942d 100644
--- a/public/credstore.te
+++ b/public/credstore.te
@@ -12,6 +12,8 @@
 add_service(credstore, credstore_service)
 allow credstore sec_key_att_app_id_provider_service:service_manager find;
 allow credstore dropbox_service:service_manager find;
+allow credstore authorization_service:service_manager find;
+allow credstore keystore:keystore2 get_auth_token;
 
 r_dir_file(credstore, cgroup)
 r_dir_file(credstore, cgroup_v2)