Is your feature request related to a problem? Please describe.

Steps to reproduce the behavior:

1. Run generate process in background.
2. Let it complete.
3. ilab process list. Check that the process is listed.
4. Repeat (3). Info about the process is gone.

This makes for bad UX.

Describe the solution you'd like

ilab process list should allow to see completed processes even after it listed it once before.

Additional context

Since the number of completed processes may be non-negligible, and they may over time clutter the UI, it may be wise to consider adding filters to process list command, e.g. ilab process list --all, ilab process list --completed, ilab process list --running, `ilab process list --errorred).

Once we no longer prune processes from the list automatically, we may need to introduce a separate ilab process prune command, or have some other means to clean the list up. (ilab process remove?)