Various unit test fixes.

[grokys]

Various unit test fixes:

• Applies Don't register MainThreadScheduler when in unit tests. editor-tools/ReactiveUI#1 to our ReactiveUI submodule. This makes tests run a lot more stably (at least in ncrunch, should also improve other test runners too)
  • This means we can remove the TestUtils.WithScheduler(Scheduler.CurrentThread) hacks
• Allow running tests in parallel in ncrunch (greatly speeds up test time)
• Fix or ignore a load of CA warnings in unit test projects

[codecov]

Codecov Report

Merging #1997 into master will decrease coverage by 1.41%.
The diff coverage is 37.5%.

@@            Coverage Diff             @@
##           master    #1997      +/-   ##
==========================================
- Coverage    41.7%   40.28%   -1.42%     
==========================================
  Files         373      405      +32     
  Lines       16126    17347    +1221     
  Branches     2211     2392     +181     
==========================================
+ Hits         6725     6988     +263     
- Misses       8890     9837     +947     
- Partials      511      522      +11

Impacted Files	Coverage Δ
...ViewModels/GitHubPane/PullRequestCheckViewModel.cs	1.09% <0%> (ø)	⬆️
...Exports.Reactive/Collections/TrackingCollection.cs	90.92% <0%> (ø)	⬆️
src/GitHub.App/Services/StandardUserErrors.cs	64.92% <0%> (ø)	⬆️
...wModels/TeamExplorer/RepositoryPublishViewModel.cs	93.45% <100%> (ø)	⬆️
...p/ViewModels/Dialog/RepositoryCreationViewModel.cs	91.32% <100%> (ø)	⬆️
src/GitHub.App/Services/ModelService.cs	31.71% <50%> (ø)	⬆️
...ineReviews/Services/PullRequestStatusBarManager.cs	0% <0%> (ø)	⬆️
...rc/GitHub.VisualStudio/Commands/OpenLinkCommand.cs	0% <0%> (ø)
...Hub.VisualStudio/Commands/ShowGitHubPaneCommand.cs	0% <0%> (ø)
...o/Commands/GoToSolutionOrPullRequestFileCommand.cs	0% <0%> (ø)
... and 30 more

[jcansdale]

I can confirm this is working a lot better! 🎉

When I first tried it, I forget to update the ReactiveUI submodule and tests were breaking all over the place. Updating the submodule turned (almost) everything green!

We still have a troublesome FilterTitleRun2 flaky test. Shall we disable it at part of this PR?

[jcansdale]

Just one suggested change. Merge at will....