[Feature Request] Switch to use xUnit test framework and runners

[Cheesebaron]

I personally much prefer xUnit test framework and runners for mobile apps. Would be great if that was supported in the templates instead.

[Plac3hold3r]

I personally do not have a preference. I initially went with the default Xamarin unit testing templates.
Out of interest is there some feature of xUnit that are better suited for mobile? I know that you switch MvvmCross's unit tests over to xUnit in version 6.xx. I'll have a look into adding xUnit as an option.

[Weldryn]

It would be very nice to have a single .netstandard test library using xUnit.net that get used by all platform test project. Then each platform would use the xUnit.runner.device. That also would allow this project to target more platform (Tizen etc). I am currently trying to do that just now.