[Proposal] Support builtin service

[Lynskylate]

RPC frameworks usually provide built-in services to offer basic observability and debugging capabilities, helping users troubleshoot issues.E.g brpc builtin service

We can provide the following capabilities (or more)：

• Memory Perf
• Cpu Perf
• Stats / Metrics
• Graceful Offline
• Service Status(healthy, endpoint)
• Connections Status