UCT/EP: Enhance uct_ep_check (#11495)

UCT/EP: Enhance uct_ep_check to support asynchronous completion callbacks

- Modified uct_ep_check to accept a completion callback, allowing for asynchronous reporting of peer status.
- Updated related functions across various transport implementations to handle the new completion parameter.
- Added tests to verify the correct behavior of the asynchronous completion mechanism during endpoint checks.