chore: added gql decorator and complexity plugin

packages/hoppscotch-backend/src/decorators/gql-user.decorator.ts

@@ -0,0 +1,17 @@
+import { createParamDecorator, ExecutionContext } from '@nestjs/common';
+import { User } from '../user/user.model';
+import { GqlExecutionContext } from '@nestjs/graphql';
+
+export const GqlUser = createParamDecorator<any, any, User>(
+  (_data: any, context: ExecutionContext) => {
+    const { user } = GqlExecutionContext.create(context).getContext<{
+      user: User;
+    }>();
+    if (!user)
+      throw new Error(
+        '@GqlUser decorator use with null user. Make sure the resolve has the @GqlAuthGuard present.',
+      );
+
+    return user;
+  },
+);