Add support for network manager and wpa-supplicant in network module

[guysoft]

Creates a file wifi.nmconnection in the boot folder if used, and lets you set up a NetworkManager connection.

I kept it low level so people can put more exotic settings in the file, for example static ips, multiple ips. etc.

Internally it copies the file each boot - would be happy to get a better solution than that. but the permissions got to be 600.

Fixes #219
Related:
raspberrypi/bookworm-feedback#72

[guysoft]

Asked here NetworkManager if we need to generate a uuid or not:
https://lists.freedesktop.org/archives/networkmanager/2024-August/000333.html

[ingojaeckel]

Thanks for putting this together! I am testing this in this repo: https://github.com/ingojaeckel/go-raspberry-pi-timelapse/releases/tag/0.5.0

Thanks to your branch, I was able to get my wifi hotspot working again on boot on a RPI Zero W 1.1 on the latest raspios lite (debian 12 bookworm). Only "changes" I needed was

• provide my own wifi.nmconnection file via /boot/firmware/wifi.nmconnection (here)
• to speed up boot, add systemctl disable NetworkManager-wait-online.service (here)

[guysoft]

@ingojaeckel Thats cool!
Your comment also comes in a good time because we are just at a crossroad to decide if this PR will get in or this one:
#230
I was not sure if to keep this, but if you are using it then it makes sense to merge and have all 3 options.

Also Cool! - do you want to add https://github.com/ingojaeckel/go-raspberry-pi-timelapse/tree/main/timelapsepi to the README of CustomPiOS? You can PR to this section:
https://github.com/guysoft/CustomPiOS?tab=readme-ov-file#list-of-distributions-using-custompios

[guysoft]

Merged, we also have a work in progress to add a new headless_nm module that would become the default option. I am merging this so CustomPiOS v1 has some option to configure network manager.