udev-rule: rework logging about udev rules

udev-rule: rework logging about udev rules

This makes the loggers take the most relevant object, i.e. when
applying udev rules to a device, the loggers take sd_device and
UdevRuleToken object, and when parsing udev rules, they take
UdevRuleLine or UdevRuleFile object.

To achieve that, this drops 'iterators' in UdevRules or friends named
`current_file` or so. Instead of that, each object now has its
parent object, e.g. UdevRuleToken.rule_line that references the
UdevRuleLine object the token belonging to. And each function previously
took UdevRules object now takes the most relevant object, e.g. UdevRuleToken.

Solves the discussion in https://github.com/systemd/systemd/pull/26698#discussion_r1129261193.