Consider rewriting netcardconfig / evaluate best practices in 2020+

[mika]

netcardconfig is hard to maintain for a bunch of reasons, including:

• one single big shell script with lots of environment variables
• lots of assumptions from many years ago (especially related to WiFi) which might not make sense anymore (with today's hardware + software stack)
• no unit/systems tests (hard to modify anything - bugs as well as new features - without breaking something™)

Known limitations/missing support for:

• 802.1X network authentication (see 802.1X network authentication seems not supported by netcardconfig grml#29)
• WPA 1/2 Enterprise WiFi networks (see WPA 1/2 Enterprise WiFi networks seem not supported by netcardconfig grml#28)
• configuring interfaces immediately brings them down/offline before configuration finished (see netcardconfig: configuring interfaces immediately brings them down/offline before configuration finished #8)

We should re-evaluate whether ifupdown is still the preferred choice for Grml in 2020 (its last upload dates back to 2019-01-28 as of 2020-07-18 and it's even up for adoption, see https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=963891), or whether switching to NetworkManager, systemd-networkd or alike, and from wpa-supplicant towards iwd could improve our situation.

One tricky part for sure will be integration with live-boot(-grml) and network configuration from within initramfs, though it would be even better if we could get rid of klib-util's ipconfig and clean up the ip=... mess. Related issues are e.g. grml/live-boot-grml#7, grml/grml#116, grml/grml#86.

If anyone has suggestions/feedback/... please us me/us know!