feat: Implement etcd and kafka auth. (#3394)

* feat: Implement etcd and kafka auth.

* Update etcd command contents.

* update contents.

* feat: update auth logic to compatible old version.

* update comment.

* update contents.

config/discovery.yml

@@ -1,9 +1,11 @@
 enable: etcd
 etcd:
   rootDirectory: openim
-  address: [ localhost:12379 ]
-  username: ''
-  password: ''
+  address: [localhost:12379]
+  ## Attention: If you set auth in etcd
+  ## you must also update the username and password in Chat project.
+  username:
+  password:
 
 kubernetes:
   namespace: default
@@ -17,4 +19,4 @@ rpcService:
   group: group-rpc-service
   auth: auth-rpc-service
   conversation: conversation-rpc-service
-  third: third-rpc-service
+  third: third-rpc-service