RDX: Implement process groups on Linux

[mook-as]

Actual Behavior

In #7965 we disabled the use of process groups on Linux (for #7945) because Electron doesn't start its own process group. We should make this happen correctly (or do equivalent things, possibly via cgroups) so that we can have a better chance of shutting down processes started by extensions.

Steps to Reproduce

(Via code inspection from the PR)

Result

We are not terminating processes by process groups, nor any other means of ensuring orphaned child processes are removed.

Expected Behavior

Do something to ensure descendant processes from extensions are terminated on factory reset and application exit.

Additional Information

No response

Rancher Desktop Version

1.17.0-hackweek-release-254-g77398647d (1.17.0-RC1)

Rancher Desktop K8s Version

N/A

Which container engine are you using?

containerd (nerdctl)

What operating system are you using?

Other Linux

Operating System / Build Version

openSUSE Leap 15.6

What CPU architecture are you using?

x64

Linux only: what package format did you use to install Rancher Desktop?

None

Windows User Only

No response