Refactor metadata app

Update permission variable name from
"permission_document_metadata_" to "permission_metadata_".

Fix failing tests.

Add test for same metadata type mixin.

Split metadata add and remove test into test for GET and
POST requests.

Remove use of urlencode and instead use furl.

Simplify view using self.action_count and
self.action_id_list.

Use ExternalObjectMixin to remove repeated code.

Move the repeated code to test for all documents to
be of the same type into its own mixin.

Signed-off-by: Roberto Rosario <Roberto.Rosario@mayan-edms.com>

mayan/apps/metadata/apps.py

@@ -48,8 +48,8 @@ from .links import (
 )
 from .methods import method_get_metadata
 from .permissions import (
-    permission_document_metadata_add, permission_document_metadata_edit,
-    permission_document_metadata_remove, permission_document_metadata_view,
+    permission_metadata_add, permission_metadata_edit,
+    permission_metadata_remove, permission_metadata_view,
     permission_metadata_type_delete, permission_metadata_type_edit,
     permission_metadata_type_view
 )
@@ -130,10 +130,10 @@ class MetadataApp(MayanAppConfig):
 
         ModelPermission.register(
             model=Document, permissions=(
-                permission_document_metadata_add,
-                permission_document_metadata_edit,
-                permission_document_metadata_remove,
-                permission_document_metadata_view,
+                permission_metadata_add,
+                permission_metadata_edit,
+                permission_metadata_remove,
+                permission_metadata_view,
             )
         )
         ModelPermission.register(