plugin/file: expand SVCB/HTTPS record support (#7950)

* plugin/file: expand SVCB/HTTPS record support

Add proper SVCB (type 64) and HTTPS (type 65) handling:

- Additional section processing: include A/AAAA glue for in-bailiwick
  SVCB/HTTPS targets, matching existing SRV/MX behavior
- Target name normalization: lowercase SVCB/HTTPS Target on zone insert,
  consistent with CNAME/MX handling
- Metrics: add TypeSVCB to monitored query types (TypeHTTPS was already
  present)
- Test helpers: add SVCB()/HTTPS() constructors and Section comparison
  cases
- Tests: basic queries with glue, AliasMode, wildcards, NoData, NXDOMAIN,
  target normalization, and DNS-AID private-use key (65400-65408)
  round-trip

Signed-off-by: Ingmar <ivanglabbeek@infoblox.com>

* plugin/file: simplify HTTPS target access via field promotion

dns.HTTPS embeds dns.SVCB, so .Target is directly accessible
without the redundant .SVCB. qualifier. Fixes gosimple S1027.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Signed-off-by: Ingmar <ivanglabbeek@infoblox.com>

---------

Signed-off-by: Ingmar <ivanglabbeek@infoblox.com>
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

plugin/file/lookup.go

@@ -409,6 +409,10 @@ func (z *Zone) additionalProcessing(answer []dns.RR, do bool) (extra []dns.RR) {
 			name = x.Target
 		case *dns.MX:
 			name = x.Mx
+		case *dns.SVCB:
+			name = x.Target
+		case *dns.HTTPS:
+			name = x.Target
 		}
 		if len(name) == 0 || !dns.IsSubDomain(z.origin, name) {
 			continue