Add query event system methods to the ApiUtil

Closes #1522

So this is what I propose. We add the 2 methods to the ApiUtil:

Here we add 2 methods to ApiUtil:

1. query_event_system: returns info about both sides of event system for this server supplier (if running) and proxy consumer
2. enable_event_system_perf_mon: enables/disables event system performance counter for this server supplier (if running) and proxy consumer

Since both methods exist in DServer and ApiUtil, their implementation was generalized and moved to Tango::detail

I also added Catch2 tests and all seems to work

And this is PyTango related MR: pytango!896