This commit ensures that WebFlux's RequestMethodsRequestCondition
supports HTTP methods that are not in the RequestMethod enum.
- RequestMethod::resolve is introduced, to convert from a HttpMethod
(name) to enum values.
- RequestMethod::asHttpMethod is introduced, to convert from enum value
to HttpMethod.
- HttpMethod::valueOf replaced Map-based lookup to a switch statement
- Enabled tests that check for WebDAV methods
See gh-27697
Closes gh-29981