Only able to pause when a stack is selected.

[joelday]

1. VSCode won't send a pause command when there is no stack selected. (The majority of the time, there are none running long enough to actually select.)
2. When we do pause, (not via breakpoint), we send a stop event immediately, but no stop event to tell the client which stack we've stopped on once a stack is actually stopped on.

Side note: @Scrivener07 Should we be treating actively executing stacks as our "threads" or should we be listing all script attachments, where each is 'paused' unless there is an active stack. I assume this list would be pretty big. Active ones could be sorted to the top? Unsure.

[joelday]

Depends on https://github.com/microsoft/debug-adapter-protocol/issues/66

[slacksystem]

I'm a bit confused by this sorry. When I set breakpoints in a file, they don't pause. Is this saying that that is due to me having to select that script in the call stack section first and is there a solution that will allow me to do so since it doesn't stay on the screen for more than a moment? @joelday I was confused by our comment on July 17

[joelday]

https://github.com/microsoft/debug-adapter-protocol/issues/66 was closed as by design, so we need to add a phony "main" thread used exclusively for handling pause requests that result in breaking on the first execution that follows. Will need to make sure that the phony thread is ignored otherwise.