Log scope to test output

[carlin-q-scott]

Is your feature request related to a problem? Please describe.
I use logger scopes to add call stack context to all my log messages, but that information isn't output to the XUnit test log.

Describe the solution you'd like
I'd like the XunitTestOutputLogger to work like the standard console logger which appends the logger scope to the end of the output message.

Describe alternatives you've considered
Forking the logger in this project to add this feature.

[owns]

You can see here there's just a dummy nullable instance added.
Looking at Microsoft's default implementation, it doesn't look too hard, but I've never personally used scopes.