Fix bad context state after debugging

[rjmholt]

Fixes PowerShell/vscode-powershell#2364.
Fixes PowerShell/vscode-powershell#2488.
May fix PowerShell/vscode-powershell#2396.

After debugging is stopped, the PowerShellContextService was being marked as being in session state aborted. Now we set the state to ready.

This fix isn't ideal, since it's made without a full understanding of the conceptual state machine of the PowerShellContextService, but it does fix the issues for the coming release while we sift through the actual architectural cause of the problem (and ideally fix it down the line)

[SeeminglyScience]

Can you test CTRL + C in various situations? Like hit a debugger stop, manually run Start-Sleep 10, try to CTRL + C?

I feel like I did something like this early on and it broke something but I can't remember what or why...

[rjmholt]

Like hit a debugger stop, manually run Start-Sleep 10, try to CTRL + C?

This one seems to work nicely.

I imagine there is an issue somewhere here. But if we don't find it, I think this change should go in, since the devil we know is quite bad

[rjmholt]

Ah, it's the second Ctrl-C that gets ignored. I'm ok with that one for now. If we can find a better implementation before Tuesday, we can put it in this PR. Otherwise will bugfix it later

[rjmholt]

@SeeminglyScience do you know where we process ctrl C? I'd like to get a better picture of what's going on so I can think about what a fix might look like

[rjmholt]

Ok, I've now made it so that sleep 10 works. I'm not sure if this could corrupt some state, but it seems not to have in my limited uses.

Basically abort opportunistically tries to acquire the lock to fire the execution status changed event. If there's a command running, it won't get the lock and no event is fired.

[SeeminglyScience]

As long as ctrl c isn't broken I'm cool with this as a temp fix. Maybe we should get an issue opened to take a pass at this for vnextnext.