- VisualStudio defaults to adding a `<none>` link item when right click -> add existing item for Razor files; therefore, this also includes the knowledge of the "None" item group when finding Razor files.
- Added unit and functional tests to verify the new `FallbackRazorProjectHost` behavior.
- Added new schema items to represent the `Content` and `None` item type information (pulled from the project system repo).
#2373
