This change intoduces content changes to our project snapshots. We now
know the open/closed state of documents that are initialized by the
Razor project system and listen to the correct data source based on
whether the file is open in the editor.
There are a few other random improvements in here as well like a
workaround for the upcoming name change to our OOP client type.
The project snapshot now maintains a RazorProjectEngine as well as set
of Tag Helpers that are known for that snapshot.
Pivoted some more services to be snapshot-centric.
Also added the ability to track .cshtml documents to the project system.
For now most components just ignore document changes.
Step 1: Add HostProject
This is a somewhat complex addition to the ProjectSnapshotManager. Now
that we accept updates from the underlying IDE project system we need to
coordinate those with the Workspace.
This means that ProjectSnapshot itself now also has a version concept.
Step 2: Introduce a new project system based on CPS
We use project capabilities defined by the Razor SDK to determine
whether to rely on MSBuild evaluation to detect the configuration or
whether to fallback to assembly-based detection.
Step 3: Flow RazorConfiguration everywhere
We use now expose the RazorConfiguration to the language service and
editor. This means that we no longer need to detect the project's
configuration asynchronously, it happens much faster now.