How to detect who is calling the adapter

[OsirisTerje]

See this discussion: microsoft/testfx#6494

The code in the adapter have used different ways to figure this out. As each caller have a different way of providing arguments to the adapter, we need to know WHO is calling us.

The code that XUnit is now using when in MTP mode: https://github.com/xunit/xunit/blob/f73db5fbfeb1ba804af03def266b1d0486205409/src/xunit.v3.runner.inproc.console/TestingPlatform/TestPlatformTestFramework.cs#L269-L270