fix(middleware/cors): export CORSOptions type

[aryasaatvik]

Exports the CORSOptions interface to allow external usage of the CORS middleware configuration type.

The author should do the following, if applicable

• Add tests
• Run tests
• bun run format:fix && bun run lint:fix to format the code
• Add TSDoc/JSDoc to document the code

[yusukebe]

Hi @aryasaatvik

Basically, we don't export option types of built-in middleware like CORSOptions, BasicAuthOptions, CompressionOptions, and others. So, honestly, I don't want to export the type as much as we can. If we allow exporting CORSOptions, we may have to export other option types. This may be fine, but "exporting something" means increasing maintenance costs. So, I can't decide if we merge this immediately.

[yusukebe]

@aryasaatvik

If you want to get the type, you can use Parameters without importing CORSOptions.

type Options = Parameters<typeof cors>[0]