[FEATURE] Add cellular network connections support

[marthabo]

Submission checklist

• I have searched existing issues and confirmed this has not been requested before.
• I have checked existing pull requests for similar changes.

Feature type

New functionality

Feature summary

Add signal strength and/or the connection status from ModemManager to the bar and network dropdown.

Motivation / use case

I know it's an incredibly niche use-case, however I'm now in a situation where I need the ability to control cellular connections quickly and effortlessly. When using Noctalia i have to control the modem using mmcli and go to the terminal every time I want to check the signal strength.

Proposed solution

A separate tab for cellular connections just like wifi and wired networks and a signal indicator in the bar. I think GNOME's implementation could be a good reference for which options are needed in the settings.

Alternatives considered

No response

References / related projects

No response

Additional context

No response