Cross-plat remoting tests need to be available for PowerShell Core

[JamesWTruher]

testability

we need to test between all the available platforms (Core and Full) as well as SSH/OMI
see: https://github.com/PowerShell/PowerShell/blob/master/docs/testing-guidelines/TestRoadmap.md

[SteveL-MSFT]

We also need to include perf comparison between PSRP over SSH and WSMan. Also scale for fan-out.