Describe the bug

systemd depends on libraries (e.g. libfido2) which in turn depend on systemd. This cycle is currently broken by using systemdMinimal, a systemd version with all optional dependencies disabled. This has these problems:

• people have to manually opt-in to systemdMinimal when they need udev or libsystemd or risk a dependency cycle
• people misuse systemdMinimal to get a minimal systemd (which it is not really intended)
• everyone gets two copies of systemd binaries and libraries in their system closure wasting 10-15 MiB.

@RaitoBezarius suggested that this could use a real bootstrap flow. Another solution would be to split building systemd libraries into a separate derivation. One wrinkle here is that libsystemd.so seems to hardcode the systemd bin/ path...

Notify maintainers

@RaitoBezarius @flokli @Mic92 @kloenk