QUrl interprets a single number as an ip address, so the track URL cdda://1
would become cdda://0.0.0.1. A previous fix addresses this issue by adding an
extra character "a" to the affected URLs then removing the last instance of the
character upon usage. However, this didn't apply when a path was present
(cdda:///dev/sr0/1), but would still attempt to reverse the change later
(cdd:///dev/sr0/1).
This change applies the fix-up to all cdda urls and moves the conversion
utilities to a single location.
See: 335bc89c9 ("Workaround for broken CD playback in Qt5 (#6021)")
This still doesn't work because the API has changed and track listings are
now delivered via a bus message instead of direct access to the struct's
members.