Notifications behave, thanks to a proper bug report

Unplugging a dock posts one notification, not a lottery. macOS reports a
hub and the devices behind it leaving as a dribble of separate events, and
WhatCable notified on whatever slice happened to arrive together, so what got
named varied run to run. Changes now settle for about a second and a half,
then get grouped under the hub they belong to: one notification titled with
the dock, everything that left with it listed inside, each device on its own
row. Same on connect, at the cost of that small delay. Thanks to
@official-Cromatin for the methodical report and the raw captures (#551), the
test data for this fix is built from them.

"Notify on app updates" stands on its own. It was nested under the
cable-changes toggle, so turning cable notifications off silently took update
notifications with it. It is now its own switch, either can be on without the
other. Also @official-Cromatin (#550).

The test-kit probes also cast a wider net: they now match base IOKit classes
instead of a fixed list of leaf names, so port-controller variants Apple ships
next turn up in diagnostics instead of being invisible.

The one to lean on: plug and unplug a dock with things behind it and see if
the notification names the lot.