Replace DB with Store in service/user (#321)

user/migrate/entity/entity.go

@@ -0,0 +1,17 @@
+package entity
+
+import (
+	"fmt"
+	"time"
+)
+
+type Row struct {
+	Id        string
+	Data      string
+	CreatedAt time.Time
+	UpdatedAt time.Time
+}
+
+func KeyPrefix(tenantId string) string {
+	return fmt.Sprintf("user/%s/", tenantId)
+}