Handle new HTTP statuses from Spring 7

[DidierLoiseau]

• This is actually a follow-up from Replace UNPROCESSABLE_ENTITY with UNPROCESSABLE_CONTENT in UpgradeSpr… #1134 as I’m afraid it will get lost.

That ticket covered HttpStatus.UNPROCESSABLE_ENTITY but there are actually more deprecations in HttpStatus in 7.0, as well as the related ones in StatusResultMatchers.

It would be nice to have recipes to cover them. 🙂