`media-type-form-p` always (or almost) returns nil

[mooseyboots]

hi, i'm playing around with this to get it running, calling it against https://codeberg.org/swagger.v1.json.

one issue i ran into was form-data parameters for file uploads.

(media-type-form-p consumes-media-type) always returns nil, because it expects a full MIME type string, but consumes-media-type is a subtype string.

consumes-media-type is created like so: (when consumes-media-types (select-media-type consumes-media-types)).

but select-media-type takes a list of MIME types and returns a subtype. e.g. if handed ("multipart/form-data") it returns "form-data".

i wasn't sure if the error is that media-type-form-p should use say serapeum:string-suffix-p as the test function, or if select-media-type should return a full MIME type string rather than a subtype.

because media-type-form-p fails, there are functions getting/setting data in req-body, but there is no such variable defined.

[mooseyboots]

using serapeum:string-suffix-p as the test function seems to work ok in my test case at least. we now have form-params rather than req-body, and the resulting code now compiles.

added the provisional fix here: https://codeberg.org/martianh/openapi2cl/src/branch/dev