feat(ZoneParserIter): Enable iter for zonefile parsing #635

Fixes #634

Add a wrapper around NewZoneParser()/Next() so that zonefiles may be parsed using Go iterators.

ZoneParserIter can be used as follows:

 for rr, err := range ZoneParserIter(strings.NewReader(mystring), "example.com", "zone.example.com") {
 if err != nil {
 return err
 }
 fmt.Printf("%s\n", rr.String())
 }

This is my first Go iterator. The name ZoneParserIter might not be best. Open to suggestions.

Nice idea!

dns.Msg has one as well:

// RRs allows ranging over the RRs of all the sections in m. This includes the question, pseudo and stateful// sections.func(m*Msg)RRs()iter.Seq[RR]{

for parsing a zone, this iter should be method on *ZoneParser and probably also called RRs

welcome to codeberg :)

I have morphed this into #636, making these changes:

• method in zp, called RRs()
• simplfied the iter function a bit - think this still correct
• example usage is now an Example test
• kept your test

also saw the error was never returned, so the iter's loop needs to be different, added test case to test for this .

see (merged) #636