- test class can now use the `MvcTestFixture`
- #3139 part 3 of 3
- dump instrumentation data at end of `_Layout.cshtml`
- include `FilePath` in display
- compare against new `.html` resource
nits:
- normalize line endings to CRLF for consistency with other tests
- add `InstrumentionData` to avoid `Tuple`
- make `TestPageExecutionContext` class `private`
- remove newly-unused actions and associated `.cshtml` files
