Warn about overhead of certain scenarios

[gambit9009]

Moved from other DiagManager Issues

Some of our scenarios like, "Detailed Performance", capture enough data points to possibly cause performance overhead. (begin & complete, statement level, transactions, query plans, etc). Adding some other events manually could cause overhead on an system already having perf issues.
couple of examples...
...."wait_info" event(Scheduling))
...events that could be redundant(like adding all the showplan's)
...large number of batches/sec (and I know "large" depends on perspective)
....anything on a busy system that ends up collecting large 100's of GBs or TB worth of data

We could update the tool to be more clear on the POSSIBLE overhead some of these scenarios can place on a system or combinations of scenarios.

And/or show a count of the number of Events that will be collected based on the current selected events. Maybe on XEvent, Trace and Profiler tabs.

[PiJoCoder]

We can add some text to the email out for customers. Plus add a notification in the pssdiag.ps1 maybe.