Description

Write a comprehensive RFC describing the way the in-process vstest.console wrapper works.
Don't forget to include corner cases and limitations.

See:

• dotnet testhost crash
• CC not working
• original PR

Limitations:

• When loaded inside a netcore process (which should be the case now), the in-proc wrapper cannot benefit from AppDomain isolation and automatic unloading anymore. Because of that we may end up seeing build failures due to locked files when doing attachment post processing (i.e. CC attachment merging).
• Dependencies of in-proc wrapper will mix with dependencies of the parent process when using the wrapper via Assembly.LoadFrom. Better dependency isolation is needed.