Feature: request ticky samples to be emitted at a specific time to the eventlog

Related: !12399 (merged)

I found it useful to be able to have ticky sample counts emitted to the eventlog at specific times. We can combine it with markers in the eventlog to filter/group counts by activity of the program.

The implementation in the linked MR worked for me (on GHC 9.6), but I'm not sure if some locking/synchronization/barrier is needed for a fully correct implementation.