Add support for new Jakarta EE RESTful Web Services multi-part form

[tjquinno]

Jakarta REST 3.1 now supports multipart form data jakartaee/rest#418

It would be great if SmallRye OpenAPI added support for this.

[MikeEdgar]

This may end up just being a change to the tests. From what I see, the new EntityPart class would be used for Jakarta REST multipart and would require user-provided annotations to give meaningful schema information.

[MikeEdgar]

@tjquinno I checked this again and I don't think there are any scanner changes to support this. Using the existing annotations to document multipart form properties is the way to go. If this appears to not be the case, we can revisit/reopen this issue.