[CLU] Moving models to root (Azure#25039)

* Change to autorest

* Changed namespace of custom models

* Regenerated

* Added CodeGenMember to BasePrediction and Regeneraed

* Removed using model namespace from all files

* Regenerated NetStandards

Author: AhmedLeithy

sdk/cognitivelanguage/Azure.AI.Language.Conversations/api/Azure.AI.Language.Conversations.netstandard2.0.cs

@@ -2,7 +2,6 @@
 // Licensed under the MIT License.
 
 using System;
-using Azure.AI.Language.Conversations.Models;
 using Azure.Core;
 
 namespace Azure.AI.Language.Conversations

sdk/cognitivelanguage/Azure.AI.Language.Conversations/src/AnalyzeConversationOptions.cs

@@ -4,7 +4,6 @@
 using System;
 using System.Threading;
 using System.Threading.Tasks;
-using Azure.AI.Language.Conversations.Models;
 using Azure.Core;
 using Azure.Core.Pipeline;