Add get_metrics and get_debug_info to rpc agent (#30833)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/30833
[rpc] Add get_metrics and get_debug_info to rpc agent
Test Plan: UT and builds
Reviewed By: mrshenli
Differential Revision: D18835068
fbshipit-source-id: f552cf196bb6d54ccd38a44ba981e7d5b15513f0
