[Feature Request] codegen: add support for suffixed content types

[Iilun]

Hello maintainers.

Once again thank you for the work on codegen.
I have been using it, and came to realize that RFC6839 suffixed content types are not supported.

These are application/XXX+json or application/XXX+xml.

These are used in a variety of standards, like:

• RFC6902: application/json-patch+json
• RFC7396: application/merge-patch+json
• RFC9457: application/problem+xml & application/problem+json

Since the part before the suffix is only for semantic meanings, it is coherent to have the generate treat them as their standard format counterparts.

I have worked on an implementation, let me know if you wish me to open the PR.

Thank you for your time