- Added a `FileChangeTracker`, `FileChangeTrackerFactory` and corresponding implementations. These types now enable us to implement Windows and Mac file change tracking instead of replacing the entire import manager.
- Changed the import manager to be a Roslyn based service.
- Moved import manager implementation to the editor.razor assembly now since it no longer depends on windows.
- Updated import manager unit tests.
- Added import manager integration test
- Added file change tracking tests.
#1804
