OpenAPI document generator should support multipart/form-data

[spericas]

Jakarta REST 3.1 now has support for this (jakartaee/rest#418). We need to make sure our OpenAPI document generator can handle this media type correctly.

[tjquinno]

Two parts to this:

1. code -> OpenAPI document: The SmallRye OpenAPI implementation does the annotation scanning to derive the OpenAPI document from an application. I have filed this SmallRye issue requesting that enhancement: Add support for new Jakarta EE RESTful Web Services multi-part form  smallrye/smallrye-open-api#1571
2. OpenAPI document -> code: Our OpenAPITools generator(s) will need to be enhanced to generate code using the new multipart form data annotation.