Implement require_auth with validate_request

[82marbag]

Motivation

This is a follow-up to: https://github.com/tower-rs/tower-http/pull/289 ValidateRequest is an abstraction of a validator and RequireAuthorization is an instance, but the latter has yet to be implemented in terms of the former. They now are two independent types.

Solution

RequireAuthorization is now implemented by ValidateRequest.

This is a breaking change.

[82marbag]

Next could be the async version

[82marbag]

test-msrv fails on: Error: could not compile hashbrown

[82marbag]

Any update on this?