RuntimeHints missing for WebFlux

[mhalbritter]

I had to add these hints to get WebFlux with Netty running, using the spring-native sample webflux-netty on this branch:

        hints.resources().registerPattern("org/springframework/http/codec/CodecConfigurer.properties");
        hints.reflection().registerType(DefaultClientCodecConfigurer.class, hint -> hint.withMembers(MemberCategory.INVOKE_PUBLIC_CONSTRUCTORS));
        hints.reflection().registerType(DefaultServerCodecConfigurer.class, hint -> hint.withMembers(MemberCategory.INVOKE_PUBLIC_CONSTRUCTORS));
        RuntimeHintsUtils.registerAnnotation(hints, RequestMapping.class);

I only did the minimal possible work that the sample passes, so I guess this is far from being complete.