The DBus API already exposes the parsed machine-tags list via the Tags
property but varlink clients needed to parse the raw TAGS= line from
MachineInformationData (which also required implementing tag name
validation if the tags would later be used with SetTags, to avoid
spurious errors).
So, provide the same information that DBus gets (a list of pre-parsed
tags with bad tags gracefully removed) as a new MachineTags field
returned by Describe -- this does mean that the DBus API now exposes the
same data in two ways but making Describe() consistent is more important
and mirrors the OperatingSystem* class of properties.
Aleksa Sarai
44cc69769d