Non-stop mode debugging

[dlipovetsky]

Is your feature request related to a problem? Please describe.
While using the debugger, I want to stop a specific goroutine, while other goroutines continue to run.

Use cases include:

• Investigating data races between goroutines.
• Stepping through code while a separate goroutine continues to respond to external requests, e.g., health checks.

Describe the solution you'd like
Support for this mode in UI, or the launch configuration, and relevant changes to the DAP client.

Describe alternatives you've considered
N/A

Additional context
This feature depends on support for a non-stop debug mode in the Delve debugger. That support, in turn, depends on changes to the go runtime.

[dlipovetsky]

I know of one extension that has support for GDB's non-stop debugging using DAP. Support was added here: eclipse-cdt-cloud/cdt-gdb-adapter#194. It might be a useful reference, at least with respect to DAP.

[findleyr]

Thanks you for the issue. I agree this would be a useful feature -- we'll look into supporting it if it becomes available in Delve (by way of golang/go#31132).

For now, moving to the backlog.