fix(dnsserver): Fix SOA record timeout issue by correcting RRSIG field formatting
- Fixed RRSIG generation by using correct field name 'signersName' (not 'signerName')
- Fixed label count calculation in RRSIG by filtering empty strings
- Added SOA records to DNSSEC signing map for proper RRSIG generation
- Added error logging and fallback values for RRSIG generation robustness
- Updated test expectations to match corrected DNSSEC RRset signing behavior
- Added comprehensive SOA test coverage including timeout, debug, and simple test scenarios
- Fix DNSSEC to properly sign entire RRsets together instead of individual records
- Implement proper SOA record serialization according to RFC 1035
- Add primaryNameserver option to IDnsServerOptions for customizable SOA mname field
- Add comprehensive tests for DNSSEC RRset signing and SOA record handling
- Update documentation with v7.4.3 improvements
Co-Authored-By: User <user@example.com>