feat: msg local cache

pkg/common/cachekey/black.go

@@ -0,0 +1,15 @@
+package cachekey
+
+const (
+	blackIDsKey = "BLACK_IDS:"
+	isBlackKey  = "IS_BLACK:"
+)
+
+func GetBlackIDsKey(ownerUserID string) string {
+	return blackIDsKey + ownerUserID
+
+}
+
+func GetIsBlackIDsKey(possibleBlackUserID, userID string) string {
+	return isBlackKey + possibleBlackUserID + "-" + userID
+}