overlay/sysusers: add fragments for all FCOS system groups

This translates all Fedora CoreOS system groups (i.e. those coming
from group manifest) into equivalent sysusers.d fragments.

We currently ship four kinds of system groups:
 * basic groups coming from the `/etc/group` file in the `setup`
   package (10-groups-basic.conf)
 * the legacy GID for the `nobody` group (00-group-nobody.conf)
 * extra groups with static GIDs that adhere to the Fedora
   allocation table (10-groups-static-extra.conf)
 * extra groups with static GIDs that are specific to CoreOS
   (00-groups-coreos-static.conf)

These sysusers.d fragments are meant as a transitory measure to
help migrate the existing group entries from the current nss-altfiles
setup to a plain sysusers.d world.

overlay.d/15fcos/usr/lib/sysusers.d/00-group-nobody.conf

@@ -0,0 +1,3 @@
+# CoreOS mismatch: https://github.com/coreos/fedora-coreos-tracker/issues/1201
+# g nobody 65534
+g nobody 99

overlay.d/15fcos/usr/lib/sysusers.d/00-groups-coreos-static.conf

@@ -0,0 +1,16 @@
+g sudo 16
+g dockerroot 986
+g cockpit-ws 987
+g systemd-bus-proxy 988
+g systemd-resolve 989
+g systemd-network 990
+g systemd-timesync 991
+g chrony 992
+g sssd 993
+g kube 994
+g input 995
+g cgred 996
+g etcd 997
+g polkitd 998
+g ssh_keys 999
+g nfsnobody 65534

overlay.d/15fcos/usr/lib/sysusers.d/10-groups-basic.conf

@@ -0,0 +1,23 @@
+g root 0
+g bin 1
+g daemon 2
+g sys 3
+g adm 4
+g tty 5
+g disk 6
+g lp 7
+g mem 8
+g kmem 9
+g wheel 10
+g cdrom 11
+g mail 12
+g man 15
+g dialout 18
+g floppy 19
+g games 20
+g tape 33
+g video 39
+g ftp 50
+g lock 54
+g audio 63
+g users 100

overlay.d/15fcos/usr/lib/sysusers.d/10-groups-static-extra.conf

@@ -0,0 +1,12 @@
+g utmp 22
+g rpcuser 29
+g rpc 32
+g utempter 35
+g dip 40
+g tss 59
+g tcpdump 72
+g sshd 74
+g dbus 81
+g ceph 167
+g avahi-autoipd 170
+g systemd-journal 190