Port api changes from 5.0 into 3.1 dotnet/sdk

[nohwnd]

• port Runsettings from command line (--) doesnt have capability to pass TestRunParameters #862 run parameters changes
• port Improving blame collector functionality of TestPlatform #2380 blame changes

/fyi @NightOwl888

[nohwnd]

Putting this into 16.7.0, but will address this probably in 16.8.0, I just don't want to forget.

[nohwnd]

looked at it earlier this morningn and we probably need to wait till 3.1.5xx branch is snapped.

@Sanan07 did you decide to tackle this one yourself? Because our last agreement was that I will do it, while you watch.

[Sanan07]

@nohwnd Sorry, you are right, I miss-read our conversation.

[nohwnd]

Skipping this, we are almost shipping 5.0 now. And 5.0 SDK can be used to build projects that target netcoreapp2.1, so there is no need to not use it.