Add Microsoft.VisualStudio.LiveShare.Razor

[NTaylorMullen]

• Added Microsoft.VisualStudio.LiveShare.Razor
• Added tests for the liveshare assembly.
• Removed GuestWorkspaceProvider because its interface (RazorLiveShareWorkspaceProvider) will be implemented by LiveShare
• Leaving RazorGuestInitializationService commented out until we have the file API from liveshare
• Made the RazorLiveShareWorkspaceProvider public so it can be implemented on the LiveShare side.
• Added LiveShare.Razor to the RazorExtension

@rynowak First commit is a direct copy of Razor.LiveShare into this repo. Second commit is the modifications to the initial code dump to include it in Razor, i'd recommend looking at the second.

@natemcmaster @ryanbrandenburg these are the bits i'm expecting my https://github.com/aspnet/AspNetCore/pull/4198 PR to enable to start generating packages for the LiveShare team (@srivatsn) to consume Leaving this PR open until all LiveShare dependencies are ready.

[natemcmaster]

Can this wait until Monday, after we finish doing the repo merge for Razor? The currently plan is to keep this repo partially building, but just for Visual Studio pieces. We're going to move most of the content of aspnet/Razor into aspnet/AspNetCore in the next hour or so.

[NTaylorMullen]

Can this wait until Monday, after we finish doing the repo merge for Razor? The currently plan is to keep this repo partially building, but just for Visual Studio pieces. We're going to move most of the content of aspnet/Razor into aspnet/AspNetCore in the next hour or so.

This wont be going into master for a few weeks. I need this branch so that we and the LiveShare team can fill in the remaining API gaps to properly include this in master.

[natemcmaster]

Ok, thanks for clarifying @NTaylorMullen

[NTaylorMullen]

Doing this in aspnet/AspNetCore-Tooling now