Asynchronous terminal output fetching and processing

[lazarosgogos]

Is your feature request related to a problem? Please describe.
While the extension is waiting for the terminal output to update its options, the screen lags for half a second (depending on the system resources of course). This is always a minor detail I would like to see improved.

Describe the solution you'd like
It would be great if the code that fetches and processes the terminal output ran asynchronously in a separate thread outside the main loop.

Describe alternatives you've considered
I tried doing it myself but failed, maybe we could collaborate and manage to do it. Any insights can prove helpful.

To Reproduce
Steps to reproduce the problematic behavior:

1. Click on GNOME's control panel (upper right)
2. Move the mouse pointer fast over the Systemd-Manager little pair of cogs icon in the tray
3. Notice the screen lagging half a second (maybe less, but still noticeable)

Environment:

• OS: Fedora Linux 41
• GNOME Shell version 47.2
• Systemd Manager version v17 (latest)