Feature proposal: support `gn` language

[anlexN]

Clear and concise description of the problem

GN is not exist in the Bundled Languages

report error:

ShikiError: Language `gn` not found, you may need to load it first

I write code block in the markdown:

```gn
use_precompiled_headers = true
```

Suggested solution

https://github.com/google/gn-language-server/

Alternative

No response

Additional context

No response

Validations

• Follow our Code of Conduct
• Read the Contributing Guide.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.

[anlexN]

@AmanCrafts @Advikkhandelwal

Thank you for your reply, you are my friend!

When can I use gn?