Failures to obtain .NET runtime are not clearly surfaced in VSCode extension

[anthony-c-martin]

Created because of #2416.

We need a way of identifying the failure to obtain .NET and surfacing this error to users.

Under dotnet.showAcquisitionLog it looks like we have an option of opening a separate output channel, but it doesn't look like this would necessarily give our extension easy access to this information.

@StephenWeatherford may have some ideas on how to approach this.

[shenglol]

When the Bicep extension is activated there will be a .NET Runtime output channel, which I believe is the one created by dotnet.showAcquisitionLog:

[alex-frankel]

Going to close since we know where this output stream lives now.

[anthony-c-martin]

Reopening as discussed in today's triage. Capturing logs programatically is not possible through the VSCode APIs provided for the dotnet runtime extension. We however wanted to update the error message to give a pointer to the https://github.com/dotnet/vscode-dotnet-runtime repo or some instructions on error reporting, so that users know how to capture the right information.