Features:
+* Turn systemd-networkd-wait-online into a small varlink service that people
+ can talk to and specify exactly what to wait for via a method call, and get a
+ response back once that level of "online" is reached.
+
+* introduce a small "systemd-installer" tool or so, that glues
+ systemd-repart-as-installer and bootctl-install into one. Would just
+ interactively ask user for target disk (with completion and so on), and then do
+ two varlink calls to the the two tools with the right parameters. To support
+ "offline" operation, optionally invoke the two tools directly as child
+ processes with varlink communication over socketpair(). This all should be
+ useful as blueprint for graphical installers which should do the same.
+
* make "systemd-vmspawn -n" work unprivileged properly, i.e. acquire tap netif
from nsresourced.