Support for non-systemd linux distributions.

[KDBalashevich]

Could you, please, make client a bit more distribution-agnostic?

Right now it requires systemd at least for two things:

1. Service management. It is not a huge problem, since a user can easily create a sysVinit/OpenRC/runit service if needed or even run the service directly.
2. DNS management. dnsutilslinux uses systemd-resolved, which is a part of systemd. In older versions it just worked with system DNS servers, but now the client does not work at all without systemd-resolved.

Could you, please, add support for openresolv or use some other solution, so that users of non-systemd distributions (like, for example, Gentoo, Alpine, Void, Devuan, Artix, etc.) could still use this software?