Incorrect description generation for mutation arguments

### Which packages are impacted by your issue?

@graphql-codegen/typescript-type-graphql

### Describe the bug

When annotating the arguments of a mutation, the generator outputs `[object Object]` rather than the description as expected.

### Your Example Website or App

https://codesandbox.io/p/devbox/winter-worker-l82rkv?file=%2Ftypes.ts%3A41%2C63-41%2C76

### Steps to Reproduce the Bug or Issue

1. Run generate

### Expected behavior

As a user I expect the descriptions of arguments on mutations to be correctly generated but they are not.

### Screenshots or Videos

_No response_

### Platform

- OS: macOS
- NodeJS: 20.9.0
- `graphql` version: 16.8.1
- `@graphql-codegen/*` version(s): 3.0.0 (@graphql-codegen/typescript-type-graphql)

### Codegen Config File

_No response_

### Additional context

_No response_