resolved: rename DnssdService "name" field to "id"

resolved: rename DnssdService "name" field to "id"

"name" is a bit confusing since this field is *not* the DNS-SD service
identifier, bust just some string derived from the .dnssd filename that
is used as handle for the service. Let's hence give it a better name:
"id".

While we are at it, switch from basename() to path_extract_filename().