This is a MEF service that can actively or passively track open ITextViews
and give us information about the Razor initialization state and eventing
when it changes.
The purpose of this is to act as a bridge between the VS mef world and the
roslyn world.
For now this doesn't do any passive tracking of Razor documents, it's only
on demand. That means it will only be initialized and used right now when
you are using the Razor developer tools. This is just to reduce our risk,
it's not ideal to ship code in VS that's doing something without anyone
looking at the result.
Ryan Nowak