machined: introduce polkit for OpenLogin() call

This way "machinectl login" can be opened up to run without privileges.
gitignore: hide test-lldp files
busctl: when introspecting objects, optionally limit output by interface name
shell-completion: add full support for completing busctl command lines, with services, objects, interfaces, members, and signatures
update TODO
hwdb: Microsoft Wireless Laser Mouse 8000 DPI data

https://bugs.freedesktop.org/show_bug.cgi?id=87587
hwdb: add rule and first entry for PS/2 mice

https://bugs.freedesktop.org/show_bug.cgi?id=87037
util: fix strict aliasing violations in use of struct inotify_event v5

There is alot of cleanup that will have to happen to turn on
-fstrict-aliasing, but I think our code should be "correct" to the rule.
sd-bus: rename sd_bus_open_system_container() to sd_bus_open_system_machine()

Pretty much everywhere else we use the generic term "machine" when
referring to containers in API, so let's do though in sd-bus too. In
particular, since the concept of a "container" exists in sd-bus too, but
as part of the marshalling system.
util: make creation time xattr logic more generic
machined: fix writability check for GPT images
import: make the dkr import URL a part of the import object, not the import name object
import: remember when we were finished importing
import: print friendly error messages on errors
import: three minor fixes
import: add a new "pull-gpt" verb for downloading GPT disk images from the internet
update TODO
update TODO
import: prefer usec_t over time_t
machined: beef up machined image listing with creation/modification times of subvolumes

We make use of the btrfs subvol crtime for this, and for gpt images of a
manually managed xattr, if we can.