Use 5.0 Diagnostic Port feature to implement trace/counter collection on startup

[josalem]

This issue will track the planning and implementation of a hypothetical dotnet {counters|trace} run verb. This verb will utilize the Diagnostic Port work done in 5.0 of the runtime to do event and counter collection on startup. A majority of the work required to do this will be shared between the two tools so the work will be tracked together.

A planning meeting hasn't occurred yet, but a few things that come to mind are:

• writing a spec for the verb
• determining whether we need to find the host
• determining whether the tool should be in charge of version gating the feature to 5.0 or newer, e.g., how should the tool fail if someone tries to run with a 3.1 runtime?
• refactor the processing pipelines to be shared between collect and run verbs

CC @sywhang @shirhatti @noahfalk @tommcdon

[sywhang]

We already shipped this in the last release - closing this issue now.