OPTIONS request should return (in the Allow header) only those methods that are actually defined

[dariok]

Assume a basic API with:

…
paths:
  /projects:
    get:
      …
    post:
      …
…

A request of OPTIONS http://localhost:8080/exist/apps/…/projects

currently returns

HTTP/1.1 200 OK
…
Allow: GET, HEAD, POST, PUT, DELETE, TRACE, OPTIONS
…

while it should only return

HTTP/1.1 200 OK
…
Allow: GET, POST, OPTIONS