Add @@clientName for RecordType in TrafficManager client.tsp (#43389)

Addresses .NET SDK PR review feedback (Azure/azure-sdk-for-net#59107):

- Rename RecordType to TrafficManagerRecordType for csharp (avoid generic name)

- Rename RecordType.AAAA to Aaaa for csharp (.NET naming convention)

- Rename RecordType.CNAME to Cname for csharp (.NET naming convention)

Author: ransinha1989

specification/trafficmanager/resource-manager/Microsoft.Network/TrafficManager/client.tsp

@@ -165,6 +165,9 @@ op getReplace(
   "csharp"
 );
 @@clientName(ProfileStatus, "TrafficManagerProfileStatus", "csharp");
+@@clientName(RecordType, "TrafficManagerRecordType", "csharp");
+@@clientName(RecordType.AAAA, "Aaaa", "csharp");
+@@clientName(RecordType.CNAME, "Cname", "csharp");
 @@clientName(MonitorProtocol.HTTP, "Http", "csharp");
 @@clientName(MonitorProtocol.HTTPS, "Https", "csharp");
 @@clientName(MonitorProtocol.TCP, "Tcp", "csharp");