feat: Implement createAuthLink mutation

packages/backend/src/graphql/root-mutation.ts

@@ -1,10 +1,12 @@
 import { GraphQLObjectType } from 'graphql';
 import createCredential from './mutations/create-credential';
+import createAuthLink from './mutations/create-auth-link';
 
 const rootMutation = new GraphQLObjectType({
   name: 'Mutation',
   fields: {
-    createCredential: createCredential
+    createCredential: createCredential,
+    createAuthLink: createAuthLink
   }
 });