Add ability for custom HTTP methods

[henryx]

Describe the feature Currently, apiBuilder permits to create only these HTTP verbs:

• GET
• POST
• PUT
• PATCH
• DELETE
• HEAD

At these methods, it can be useful to add the ability to define a custom HTTP verb

Additional context WebDAV extends standard HTTP verbs with a set of custom verbs (like PROPFIND, LOCK, COPY, MOVE...).

Hashicorp Terraform extends HTTP verbs with LOCK and UNLOCK verbs.

Ability to set an HTTP custom verb permit to create webapps that can communicate, for example, with these systems

[dzikoysk]

This is directly related to:

• https://github.com/javalin/javalin/issues/2331

But having official support in-place, we should be able to support it in api builder as well.