Bump test project dependencies

[dougbu]

Bump test project dependencies

• Castle.Core, Moq, and xUnit versions were all out of date
• hold xunit.runner.visualstudio version back in .NET SDK test projects
  • can be moved to latest version after we stop testing on netcoreapp2.1
• add missing xunit.analyzers reference to System.Web.Razor.Test project
• move all test projects to .NET v4.6.2 (a supported framework)
  • remove netstandard reference in System.Net.Http.Formatting.Test; not needed w/ new TFM & updated references
• further separate build of Microsoft.TestCommon project when invoked from NetCore.Test project
  • special case RestorePackages for this case
  • add System.Net.Http references to avoid conflicting versions e.g. src/ and test/ TFMs differ

React to changed xUnit APIs

• adjust Microsoft.TestCommon code
• nit: use Array.Empty<byte>() in TranscodingStreamTests
  • TranscodingStream internals can be private instead

Resolve xUnit issues new analyzers find

• address xUnit2000 warnings
  • pass expected values to Assert.Equal(...) as correct (left) argument
• make generic method types explicit to avoid error CS0121: The call is ambiguous between the following methods or properties: ...
• note: cannot remove unnecessary xUnit1013 suppression
  • related bug (xunit/xunit#1466) apparently not fixed in 1.0.0 analyzers package
  • was xunit/xunit.analyzers#82 fix (in 2017) insufficient?

React to new Moq changes

• avoid ProtectedMock\1.ThrowIfPublicMethod(...)`throwing
  • use new overloads introduced in the Moq 4.11.0 release
• adjust to Moq hiding the ObjectProxy type better
• update ControllerContext mocking to avoid NREs
  • setting HttpContext.User on the Object left get value null (did nothing)
• nit: use SetupGet(...) for another property