Make sure we're doing Splat.ModeDetector.Current.SetInUnitTestRunner(true) once per test project

[jcansdale]

Some of our tests appear to be failing depending on the order in which they're run. This is because SetInUnitTestRunner(true) isn't always getting called before a test is executed.

Since we're no longer using Fody, we should add the following to the AssemblyInfo.cs for each of our test projects:

[SetUpFixture]
public class SplatModeDetectorSetUp
{
    [OneTimeSetUp]
    public void RunBeforeAnyTests()
    {
        Splat.ModeDetector.Current.SetInUnitTestRunner(true);
    }
}

We should also remove IEntryExitDecorator and any other calls to SetInUnitTestRunner(true) in our test projects.

@meaghanlewis It might make sense to do this as part of #1721?

[meaghanlewis]

@jcansdale yes, I think it makes sense to do this in #1721.

I'll make sure to to add the snippet to SetInUnitTestRunner(true) to each test project and will also remove the IEntryExitDecorator calls and other Fody references.