Support the .NET Education Bundle extension pack

[baronfel]

MS has an all-in-one bundle for one-click install of the .NET SDK and a bunch of .NET extensions for VS Code here. This bundle uses a specific extension to acquire a local copy of the .NET SDK and runtime (default to latest version). Right now, Ionide doesn't work with this setup because we probe for the various installed locations ourselves, which this SDK acquisition extension doesn't install to (due to the logic being that educational users don't have admin rights).

We should have a two-tier dotnet lookup system: if this extension is installed, call its APIs to get the location of the dotnet managed by the extension, and then use the data from that dotnet to run FSAC/issue dotnet commands. If this extension is not installed, use our normal pathways.

[baronfel]

How dare you make this presumption, sir.