Unable to load .graphql files. how to add custom loader for graphq files?

## Bug Report

Before I use serverless-esbuild to config loader for .graphql files but with serverless v4 it doesn't work.

**Current Behavior**

```
Offline [http for lambda] listening on http://localhost:3002
Function names exposed for local invocation by aws-sdk:
* hello: my-service-dev-hello

┌─────────────────────────────────────────────────────────────────────────┐
│ │
│ GET | http://localhost:3000/dev/hello │
│ POST | http://localhost:3000/2015-03-31/functions/hello/invocations │
│ │
└─────────────────────────────────────────────────────────────────────────┘

Server ready: http://localhost:3000 🚀

GET /dev/hello (λ: hello)
✖ Unhandled exception in handler 'hello'.
✖ Runtime.UserCodeSyntaxError: SyntaxError: Unexpected identifier 'mutation_root'
at _loadUserApp (/Users/deathemperor/papaya/slsv4-offline/node_modules/serverless-offline/src/lambda/handler-runner/in-process-runner/aws-lambda-ric/UserFunction.js:239:13)
at async module.exports.load (/Users/deathemperor/papaya/slsv4-offline/node_modules/serverless-offline/src/lambda/handler-runner/in-process-runner/aws-lambda-ric/UserFunction.js:311:19)
at async InProcessRunner.run (file:///Users/deathemperor/papaya/slsv4-offline/node_modules/serverless-offline/src/lambda/handler-runner/in-process-runner/InProcessRunner.js:41:21)
at async MessagePort. (file:///Users/deathemperor/papaya/slsv4-offline/node_modules/serverless-offline/src/lambda/handler-runner/worker-thread-runner/workerThreadHelper.js:24:14)
✖ SyntaxError: Unexpected identifier 'mutation_root'
```

**Sample Code**

https://github.com/papaya-insurtech/slsv4-offline

**Expected behavior/code**

**Environment**

- `serverless` version: 4.4.7
- `serverless-offline` version: 14.3.3
- `node.js` version: v22.9.0
- `OS`: macOS 15.1

**Possible Solution**

N/A