Expose processes leveraged by BuildManager

[JanKrivanek]

Fixes #11051

Context

For various hangs detection we need worker processes dumps. Let's unblock VS perf team in enabling automatic collection of worker processes dumps.

Testing

No tests provided.
This is best effort, point in time functionality, that should be used so

FYI @davkean

[maridematte]

I know we also have some issues that have the error "Node # has exited unexpectedly", could a bit more information on the nodes help with that one too?

[JanKrivanek]

I know we also have some issues that have the error "Node # has exited unexpectedly", could a bit more information on the nodes help with that one too?

Tho goal of this PR is to help collect more relevant data with perfWatson on VS hangs - as important context might be in running out-of-proc MSBuild nodes, for which we are missing dumps.
If the node process crashes - then dump is already automatically collected.
So I feel there is no other information we can add here for the crashing nodes. But kick me harder if I'm missing something specific you have on mind :-)