add MESSAGE_RSOCKET_MIMETYPE and MESSAGE_RSOCKET_ACCEPT_MIMETYPES (#744)

Signed-off-by: linux_china <libing.chen@gmail.com>

rsocket-core/src/main/java/io/rsocket/metadata/WellKnownMimeType.java

@@ -72,7 +72,8 @@ public enum WellKnownMimeType {
   APPLICATION_CLOUDEVENTS_JSON("application/cloudevents+json", (byte) 0x28),
 
   // ... reserved for future use ...
-
+  MESSAGE_RSOCKET_MIMETYPE("message/x.rsocket.mime-type.v0", (byte) 0x7A),
+  MESSAGE_RSOCKET_ACCEPT_MIMETYPES("message/x.rsocket.accept-mime-types.v0", (byte) 0x7B),
   MESSAGE_RSOCKET_AUTHENTICATION("message/x.rsocket.authentication.v0", (byte) 0x7C),
   MESSAGE_RSOCKET_TRACING_ZIPKIN("message/x.rsocket.tracing-zipkin.v0", (byte) 0x7D),
   MESSAGE_RSOCKET_ROUTING("message/x.rsocket.routing.v0", (byte) 0x7E),