Support stopping a single goroutine

[dlsniper]

Once golang/go#31132 is implemented, Delve should also implement support for it.

[mangalaman93]

It'd be pretty useful to only execute one goroutine when next or step is executed. Currently, all the goroutine make progress, which makes it harder to debug a particular scenario when multiple goroutines are running. I am wondering though whether it is possible to achieve this without the support from runtime as mentioned in the issues golang/go#25578 golang/go#31132

[leos-code]

Hopefully, this feature will be supported

[hitzhangjie]

It sounds like a conditional breakpoint, the condition is goid=.

The debugger create a breakpoint there but resume the tracee if the thread.tls.goid != wantedGoID.