Extension delay reported

[jefflill]

We're sometimes seeing warnings from Visual Studio like this:

I believe this is because we're currently invoking the dotnet publish ... on the UI task.

[jefflill]

dotnet publish ... is already happening on a background task, so that's not causing this.

[jefflill]

I'll need to keep an eye out for more of these and then use this link to debug:

https://docs.microsoft.com/en-us/visualstudio/extensibility/how-to-diagnose-ui-delays-caused-by-extensions?view=vs-2019