* OpenAPI: Fix generation of correct fields
Currently, the OpenAPI generator logic is wrong about how it maps from
Vault framework fields to OpenAPI. This manifests most obviously with
endpoints making use of `framework.OptionalParamRegex` or similar
regex-level optional path parameters, and results in various incorrect
fields showing up in the generated request structures.
The fix is a bit complicated, but in essence is just rewriting the
OpenAPI logic to properly parallel the real request processing logic.
With these changes:
* A path parameter in an optional part of the regex, no longer gets
erroneously treated as a body parameter when creating OpenAPI
endpoints that do not include the optional parameter.
* A field marked as `Query: true` no longer gets incorrectly skipped
when creating OpenAPI `POST` operations.
* changelog
