Role-based ACL support in Sentinel dashboard

提个小建议。。
建议控制台可以分角色提供不同权限。
比如管理员和普通用户。只有管理员可一新增编辑限流降级等规则，普通用户只可以查看 实时监控 和 机器列表 等。否则线上环境使用很危险。

Start by locating the Sentinel dashboard entry points for rule management, real-time monitoring, and machine lists, then check whether any existing authentication or permission model is documented. The issue's intended result is role-based access: administrators can add or edit flow-control and degradation rules, while ordinary users can only view monitoring and machine information.

Written by the indexing model from the issue text.