feat: Add Data Domain Retrieval Functionality

[christopher-tin-atlan]

This PR adds comprehensive data domain retrieval capabilities to the Atlan MCP server, enabling AI agents to fetch detailed domain information including hierarchical relationships and stakeholder data within a single API call.

This is a significant improvement over the current asset and lineage tool, as the MCP will provide an optimized alternative.

What's New

• New MCP Tool: retrieve_domain_tool
• Retrieve data domains by GUID or qualified name
• Returns comprehensive domain details with relationship enrichment
• Supports both parent domains and subdomains with full hierarchy context

Comprehensive Data Return

• Basic attributes: name, GUID, qualified_name, description, certificate_status
• Metadata: created_by, updated_by, timestamps, status
• Domain hierarchy: parent_domain, sub_domains with full details
• Relationships: stakeholders with enriched information
• Domain-specific: parent_domain_qualified_name, super_domain_qualified_name

Response Structure

{
  "domain": {
    "guid": "domain-guid-here",
    "name": "Domain Name",
    "qualified_name": "default/domain/domain-name",
    "description": "Domain description",
    "certificate_status": "VERIFIED",
    "created_by": "user.name",
    "sub_domains": [
      {
        "guid": "subdomain-guid",
        "name": "Subdomain Name",
        "qualified_name": "default/domain/domain-name/subdomain",
        // ... full subdomain details
      }
    ],
    "parent_domain": {
      "guid": "parent-guid",
      "name": "Parent Domain",
      // ... full parent details
    },
    "stakeholders": [],
    // ... all other domain attributes
  },
  "error": null
}

[Hk669]

instead of a tool, lets add the examples to search_assets_tool