[PLT-4341] add dnd command (#7694)

model/status.go

@@ -11,6 +11,7 @@ import (
 const (
 	STATUS_OFFLINE         = "offline"
 	STATUS_AWAY            = "away"
+	STATUS_DND             = "dnd"
 	STATUS_ONLINE          = "online"
 	STATUS_CACHE_SIZE      = SESSION_CACHE_SIZE
 	STATUS_CHANNEL_TIMEOUT = 20000  // 20 seconds