- Instead of using Razor/Mvc TemplateEngine use `RazorProjectEngine`. This involved changing several locations (each of which used `RazorTemplateEngine` in an entirely different way) to use the RazorProjectEngine's two Process methods.
- Changed an unused public API `VisualStudioRazorParser.TemplateEngine` to `VisualStudioRazorParser.RazorProjectEngine`.
- Ported the remainder of `RazorEngineBuilder`'s extension methods over to `RazorProjectEngineBuilder`. These were used in tests and our `RazorGenerate` tool.
- Added a few test helper methods/classes to enable simple testing of the `RazorProjectEngine`.
- Resolved several test hacks that were working around little discrepancies each of the `RazorTemplateEngine` APIs.
- Changed the template engine factory service to be a project engine factory service.
- Changed all existing APIs to utilize `RazorProjectFileSystem`. This was possible because `RazorProjectFileSystem` inherits from RazorProject.
- Renamed `FileSystemRazorProject` to `DefaultRazorProjectFileSystem`.
- Renamed FileSystemRazorProjectItem` to `DefaultRazorProjectItem`.
- Obsoleted `RazorProject.Create`
#1828