WIP adding interior_refs endpoints

Ran into some limitations of sqlx while trying to bulk create interior_refs. I
also discovered how slow creating hundreds of rows in postgres is and I'm
planning on saving interior_refs data in a jsonb column instead which seems to
be much faster.

src/models/model.rs

@@ -25,4 +25,7 @@ where
     async fn get(db: &PgPool, id: i32) -> Result<Self>;
     async fn save(self, db: &PgPool) -> Result<Self>;
     async fn list(db: &PgPool, list_params: ListParams) -> Result<Vec<Self>>;
+    async fn bulk_save(_db: &PgPool, _models: Vec<Self>) -> Result<()> {
+        unimplemented!()
+    }
 }