.NET: Add missing Azure OpenAI Migration Sample code (#559)

* Add missing Azure OpenAI Migration Sample code

* Add Azure OpenAI Assistants Samples

* Address miner README typos

* Remove leftover

dotnet/samples/SemanticKernelMigration/AzureOpenAI/Step01_Basics/Program.cs

@@ -0,0 +1,67 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using Azure.AI.OpenAI;
+using Azure.Identity;
+using Microsoft.Extensions.AI.Agents;
+using Microsoft.SemanticKernel;
+using Microsoft.SemanticKernel.Agents;
+using Microsoft.SemanticKernel.Connectors.OpenAI;
+using OpenAI;
+
+var endpoint = Environment.GetEnvironmentVariable("AZUREOPENAI_ENDPOINT") ?? throw new InvalidOperationException("AZUREOPENAI_ENDPOINT is not set.");
+var deploymentName = System.Environment.GetEnvironmentVariable("AZUREOPENAI_DEPLOYMENT_NAME") ?? "gpt-4o";
+var userInput = "Tell me a joke about a pirate.";
+
+Console.WriteLine($"User Input: {userInput}");
+
+await SKAgent();
+await AFAgent();
+
+async Task SKAgent()
+{
+    Console.WriteLine("\n=== SK Agent ===\n");
+
+    var builder = Kernel.CreateBuilder().AddAzureOpenAIChatClient(deploymentName, endpoint, new AzureCliCredential());
+
+    var agent = new ChatCompletionAgent()
+    {
+        Kernel = builder.Build(),
+        Name = "Joker",
+        Instructions = "You are good at telling jokes.",
+    };
+
+    var thread = new ChatHistoryAgentThread();
+    var settings = new OpenAIPromptExecutionSettings() { MaxTokens = 1000 };
+    var agentOptions = new AgentInvokeOptions() { KernelArguments = new(settings) };
+
+    await foreach (var result in agent.InvokeAsync(userInput, thread, agentOptions))
+    {
+        Console.WriteLine(result.Message);
+    }
+
+    Console.WriteLine("---");
+    await foreach (var update in agent.InvokeStreamingAsync(userInput, thread, agentOptions))
+    {
+        Console.Write(update.Message);
+    }
+}
+
+async Task AFAgent()
+{
+    Console.WriteLine("\n=== AF Agent ===\n");
+
+    var agent = new AzureOpenAIClient(new Uri(endpoint), new AzureCliCredential()).GetChatClient(deploymentName)
+        .CreateAIAgent(name: "Joker", instructions: "You are good at telling jokes.");
+
+    var thread = agent.GetNewThread();
+    var agentOptions = new ChatClientAgentRunOptions(new() { MaxOutputTokens = 1000 });
+
+    var result = await agent.RunAsync(userInput, thread, agentOptions);
+    Console.WriteLine(result);
+
+    Console.WriteLine("---");
+    await foreach (var update in agent.RunStreamingAsync(userInput, thread, agentOptions))
+    {
+        Console.Write(update);
+    }
+}