Add delete for performers and studios

graphql/documents/mutations/studio.graphql

@@ -17,4 +17,8 @@ mutation StudioUpdate(
   studioUpdate(input: { id: $id, name: $name, url: $url, image: $image }) {
     ...StudioData
   }
+}
+
+mutation StudioDestroy($id: ID!) {
+  studioDestroy(input: { id: $id })
 }