Add missing DNS Zone commands

[Copilot]

Implements four missing OpenSRS DNS zone commands and exposes the existing DeleteDnsZoneRequest through DomainClient.

Changes

New Commands

• ForceDnsNameservers - Forces domain to use OpenSRS DNS nameservers
• GetDnsZone - Retrieves DNS records for a domain
• SetDnsZone - Updates DNS zone records
• ResetDnsZone - Resets DNS zone to template values

Each includes:

• Request/Result class pair with XML serialization/parsing
• Async method in DomainClient
• Unit test coverage

Additional

• Exposed DeleteDnsZoneAsync in DomainClient (request class existed but was not callable)

Usage

var client = new OpenSRSClient(httpClient, options);

// Get current DNS zone
var getResult = await client.GetDnsZoneAsync(new GetDnsZoneRequest { Domain = "example.com" });

// Update DNS records
var setResult = await client.SetDnsZoneAsync(new SetDnsZoneRequest 
{ 
    Domain = "example.com",
    Records = new DnsRecordSet { /* ... */ }
});

// Force to OpenSRS nameservers
await client.ForceDnsNameserversAsync(new ForceDnsNameserversRequest { Domain = "example.com" });

All implementations follow existing patterns: XPath-based XML parsing, ResponseDetails error handling, and null-safe element access.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Add Missing DNS Zone commands</issue_title>
<issue_description>We need to implement the following actions with appropriate Request and Result models:

https://domains.opensrs.guide/docs/force_dns_nameservers

https://domains.opensrs.guide/docs/get_dns_zone

https://domains.opensrs.guide/docs/set_dns_zone

https://domains.opensrs.guide/docs/set_dns_zone-

Then add methods to DomainClient to use them. Also add DeleteDnsZoneRequest to DomainClient</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Add Missing DNS Zone commands #37

---

💬 We'd love your input! Share your thoughts on Copilot coding agent in our 2 minute survey.