Add message queue agent (#6463)

* scaffold message queue agent

* adjust proto, add mq_agent

* add agent client implementation

* remove unused function

* agent publish server implementation

* adding agent

weed/pb/volume_server_pb/volume_server.pb.go

@@ -1,7 +1,7 @@
 // Code generated by protoc-gen-go. DO NOT EDIT.
 // versions:
 // 	protoc-gen-go v1.34.2
-// 	protoc        v5.28.1
+// 	protoc        v5.28.3
 // source: volume_server.proto
 
 package volume_server_pb