Replace D-Bus with a much simpler system

Looks like I am not the only one who finds D-Bus utterly confusing, overcomplicated, and badly documented. Also I have the growing suspicion that it is not fast.

https://www.hyperbola.info/todo/dbus-mitigation/

People have done it before:

> 2022-06-15 - Tobias Dausend
>
>With the release Milky Way v0.4 all parts of [D-Bus](https://www.freedesktop.org/wiki/Software/dbus/) got completely removed and all included packages within our repositories were selected to be completely usable without any message-oriented middleware and framework. We don't plan to integrate any further support for the framework also in the future for upcoming versions of Hyperbola GNU/Linux-libre and HyperbolaBSD.

https://www.hyperbola.info/news/end-of-d-bus-support/

But:

What about existing applications, including those from Linux?
We'd need at least some minimal runtime compatibility layer that would mimic D-Bus "legacy" interfaces for existing applications.