Merge branch 'MRM-4965' into 'release/v0.15'

MRM-4965 BE - Notification - creating storage of sent notifications

See merge request mashroom/backend/messaging!33

api/mashroom_messaging.proto

@@ -48,6 +48,9 @@ enum EmbedType {
   EMBED_TYPE_TOKEN          = 26;
   EMBED_TYPE_DOCUMENT       = 27;
   EMBED_TYPE_MORTGAGE_LEAD  = 28;
+  EMBED_TYPE_INVOICE        = 29;
+  EMBED_TYPE_PAYMENT        = 30;
+  EMBED_TYPE_LISTING        = 31;
 }
 
 enum Presence {