Previously we allocated subuids automatically for all normal users.
Make this explicitly configurable, so that one can use this for system
users too (or explicitly disable for normal users). Also don't allocate
automatically by default if a user already has ranges specified statically.
a few things should've used buildPackages/nativeBuildInputs to not not require
the host architecture for building docs. tested by building aarch64-linux docs
on x86_64-linux, and the result looks good.
In https://gitlab.gnome.org/GNOME/gnome-settings-daemon/-/merge_requests/153
the user target names for GSD components has been renamed for example
from `gsd-a11y-settings.target` to `org.gnome.SettingsDaemon.A11ySettings.target`,
and nowadays `gsd-*.target` are just symbolic links of `/dev/null` and will be
removed in the future.
At the same time, as mentioned in d27212d466,
we are adding `systemd.user.targets.<name>.wants` stuff here only because
systemd.packages doesn't pick the .wants directories. Nowadays those GSD components
are managed in `/etc/systemd/user/gnome-session@gnome.target.d/gnome.session.conf`
so it should be safe to remove them.
In this commit we also try to pick up those new .wants directories, see also
https://gitlab.gnome.org/GNOME/gnome-settings-daemon/-/blob/41.0/plugins/meson.build#L57
Result of `cd /nix/store/iqzy2a6wn9bq9hqx7pqx0a153s5xlnwp-gnome-settings-daemon-41.0; find | grep wants`:
```
./share/systemd/user/gnome-session-x11-services-ready.target.wants
./share/systemd/user/gnome-session-x11-services-ready.target.wants/org.gnome.SettingsDaemon.XSettings.service
./share/systemd/user/gnome-session-x11-services.target.wants
./share/systemd/user/gnome-session-x11-services.target.wants/org.gnome.SettingsDaemon.XSettings.service
```
Result of `cd /nix/store/armzljlnsvc1gn0nq0bncb9lf8fy32zy-gnome-settings-daemon-3.34.0; find | grep wants`:
```
./lib/systemd/user/gnome-session-initialized.target.wants
./lib/systemd/user/gnome-session-initialized.target.wants/gsd-a11y-settings.target
./lib/systemd/user/gnome-session-initialized.target.wants/gsd-color.target
./lib/systemd/user/gnome-session-initialized.target.wants/gsd-datetime.target
./lib/systemd/user/gnome-session-initialized.target.wants/gsd-power.target
./lib/systemd/user/gnome-session-initialized.target.wants/gsd-housekeeping.target
./lib/systemd/user/gnome-session-initialized.target.wants/gsd-keyboard.target
./lib/systemd/user/gnome-session-initialized.target.wants/gsd-media-keys.target
./lib/systemd/user/gnome-session-initialized.target.wants/gsd-screensaver-proxy.target
./lib/systemd/user/gnome-session-initialized.target.wants/gsd-sharing.target
./lib/systemd/user/gnome-session-initialized.target.wants/gsd-sound.target
./lib/systemd/user/gnome-session-initialized.target.wants/gsd-smartcard.target
./lib/systemd/user/gnome-session-initialized.target.wants/gsd-wacom.target
./lib/systemd/user/gnome-session-initialized.target.wants/gsd-print-notifications.target
./lib/systemd/user/gnome-session-initialized.target.wants/gsd-rfkill.target
./lib/systemd/user/gnome-session-initialized.target.wants/gsd-wwan.target
./lib/systemd/user/gnome-session-x11-services.target.wants
./lib/systemd/user/gnome-session-x11-services.target.wants/gsd-xsettings.target
```
This never configured where SNI should log to, as it's up to the user to
provide the full sniproxy config (which can be configured to log to a
file).
This option only produced a ExecStartPre script that created the folder.
Let's use LogsDirectory to create it. In case users want to use another
directory for logs, they can override LogsDirectory or set their own
ExecStartPre script.
