- Removed the `Microsoft.VisualStudio.Language.IntelliSense` dependency from `Microsoft.VisualStudio.Editor.Razor` because it isn't supported in VS for mac.
- Replaced `ICompletionBroker` usage in the VS agnostic dll with a new abstract type `VisualStudioCompletionBroker`. This also enables us to implement completion
- Added Mac implementation of new `VisualStudioCompletionBroker`.
#1789