feat: Implement getApp graphQL query

packages/backend/src/graphql/queries/get-app.ts

@@ -0,0 +1,11 @@
+import App from '../../models/app';
+
+const getApp = (name: string) => {
+  if(!name) {
+    throw new Error('No name provided.')
+  }
+
+  return App.findOneByName(name)
+}
+
+export default getApp;