Per RFC 7231 (https://www.rfc-editor.org/rfc/rfc7231#section-4.3.5), sending a body
with the DELETE method "has no defined semantics". Allow it, as it is useful for
passing the csrf token required by some authentication methods.
Bug: T309388
Change-Id: I9fb7f3c536af4636e33f776de32f9f90b88827c9
MediaWiki\Rest\Validator is largely a wrapper, but has some behavior
of its own which deserves testing.
Bug: T309388
Change-Id: Ida4be429fa6795a3494593c457b93ef8e4f68b3b