main/alpine-baselayout: reconsider default users/groups

The alpine baselayout includes a lot of users and groups. Some of which are to my knowledge not used or should by added by the appropriate packages.

Examples:
ntp (user/group) currently unused but should be moved to ntp packages actually using it
man (user/group) what is that even for?
abuild (group) is already created by the abuild package
vpopmail (user/group) for a package that has been removed 13 years ago
xfs (user/group) is a X font server used?

Now I am creating this issue because I don't know exactly which are used so I would appreciate some feedback.

name	keep?	notes
root (user/group)	yes
bin (user/group)	yes	legacy compatibility
daemon (user/group)	yes	legacy user for deamons, dedicated users are better
sys (group)	yes	historical
adm (user/group)	only group	system monitoring
tty (group)	yes	used by mdev/udev
disk (group)	yes	used by mdev/udev
lp (user/group)	yes	used by udev, not yet used by mdev (mdev-conf#3)
mem (group)	no	using kmem group instead (mdev-conf!11 (merged)) (!60790 (merged))
kmem (group)	yes	used by mdev/udev
wheel (group)	yes
floppy (group)	yes
mail (user/group)	yes	debian doc
news (user/group)	yes	used for news associated programs
uucp (user/group)	no	used by mdev for serial tty, replace uucp with dialout group (mdev-conf!12 (merged)), fix aports (!59845 (merged), !69231 (merged), !69933)
man (user/group)	no	moved to man-db in !58251 (merged)
cron (user/group)	no	move to cron deamons?
console (group)	no
audio (group)	yes
cdrom (group)	yes	used by mdev/udev
dialout (group)	yes	used by mdev/udev
ftp (user/group)	no	move to ftp deamons?
sshd (user/group)	no	move to ssh deamons?
input (group)	yes	used by mdev/udev
at (user/group)	no	created and used by at package, fixed in !58093 (merged)
tape (group)	yes	used by mdev/udev
video (group)	yes	used by mdev/udev
netdev (group)	yes	used by mdev
readproc (group)	no	old remnant, removed in !55375 (merged)
squid (user/group)	no	already created by squid package
xfs (user/group)	no	old gentoo remnant
kvm (group)	yes	used by mdev/udev
games (user/group)	yes
shadow (group)	yes	/etc/shadow file
cdrw (group)	no	used until 2007, now using cdrom group instead (!55378 (merged))
www-data (group)	yes	used by some web servers?, added in b881d448f79
usb (group)	no	was gentoo specific, now using dialout group instead, removed from usbmuxd in !58574 (merged), removing in !60790 (merged)
vpopmail (user/group)	no	removed related package
users (group)	yes	not needed
ntp (user/group)	yes	should be added to ntp deamons when used, TODO add to openntpd, added in 601af9ebc43
nofiles (group)	no	was used by unused qmail* users
smmsp (user/group)	no	created and used by milter-greylist
locate (group)	no	created and used by plocate
abuild (group)	no	should be moved to abuild package, added in 4f0ac3dd09f
utmp (group)	yes	used by some programms, (eg. utmps, openrc uses it when available)
ping (group)	yes	added in 3579df3582b, used to give system users (eg. daemons) ping permission
nogroup (group)	yes
nobody (user/group)	yes
sync (user)	?	sync disks without root access, would recommend adding if people want
shutdown (user)	no	we do not have /sbin/shutdown (#15453 (comment 381536))
halt (user)	?	would recommend adding if people want
operator (user)	no	historic
postmaster (user)	no
cyrus (user)	no

I think that technically video, audio, lp and more are only used by the device manager and maybe should be moved there. When a kernel driver initializes a device, the default state of the device node is to be owned by root:root, with permissions 600. If a system doesn't use the default mdev or udev config they may not need these grouos.

• clean up mkinitfs groups/users too (mkinitfs!181 (merged))
• reduce usage of nogroup/nobody/bin

An overview of all uids/gids that are/have been used can be found here: https://wiki.alpinelinux.org/wiki/User:Sertonix/Known_UID_and_GID