I've had a couple of deadlock situations when invoking win32 apps
via wsl on my work machine. In those situations, the process that
we show in the titlebar is a short lived process that has likely
recently terminated, so I suspect something weird about either
dangling references or, given the deadlock-y nature of things,
maybe trying to reference ourselves.
This commit tries to defend against these by:
* Avoiding creating a ProcHandle for our own pid
* Releasing the toolhelper snapshot as soon as we have copied
out the list of pids that we need
Not sure that this will nail it, but it seems like it can't hurt.
When considering the fg process, we don't want a newly spawned
notepad.exe to show as the fg process in a cmd/pwsh pane, as it
runs async from the console and isn't attached to it.
We can extract the console handle from the process information and
use a 0 value handle to indicate win32 apps that are not attached
to any console.
We cannot compare console handle values directly: without probing
deeper into the handle we don't know that two differently valued
handles refer to different consoles, because a handle can be
duplicated into another with a different numeric value.
