Add GlobalFilter for Gateway MVC

[Andross96]

Replicate the Spring Cloud Gateway Reactive GlobalFilter interface behavior in Gateway MVC.
Only the interface is created (and not every implementation, which are already handled within the FilterDiscoverer).

The GlobalFilter interface allows applications to create a filter bean which will be executed only on matched gateway routes. It also supports for Order annotation.

Exemple implementation:

@Configuration
public class CustomGlobalFilter implements GlobalFilter {
    @Override
    public HandlerFilterFunction<ServerResponse, ServerResponse> filter() {
        return (request, next) -> {
            LOGGER.info("Routing to route '{}'", request.attribute(MvcUtils.GATEWAY_ROUTE_ID_ATTR));
            return next.handle(request);
        };
    }
}

Fixes #3239 and #3143

[spencergibb]

I'm not sure mvc gateway requires a separate implementation of filters besides what mvc.fn provides

[spencergibb]

Sorry, I'll keep conversation in issue rather than pr

[spencergibb]

Closing in favor of #3177