.Net: Filter out reasoning response items during function calling (#13020)

### Motivation and Context

Closes #12904 

### Description

<!-- Describe your changes, the overall approach, the underlying design.
These notes will help understanding how your code works. Thanks! -->

### Contribution Checklist

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- [ ] The code builds clean without any errors or warnings
- [ ] The PR follows the [SK Contribution
Guidelines](https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
and the [pre-submission formatting
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raises no violations
- [ ] All unit tests pass, and I have added new tests where possible
- [ ] I didn't break anyone 😄

Author: markwallace-microsoft

dotnet/samples/GettingStartedWithAgents/OpenAIResponse/Step03_OpenAIResponseAgent_ReasoningModel.cs

@@ -2,6 +2,7 @@
 using Microsoft.SemanticKernel;
 using Microsoft.SemanticKernel.Agents.OpenAI;
 using OpenAI.Responses;
+using Plugins;
 
 namespace GettingStarted.OpenAIResponseAgents;
 
@@ -80,4 +81,26 @@ exceed 80 columns
             WriteAgentChatMessage(responseItem);
         }
     }
+
+    [Fact]
+    public async Task UseOpenAIResponseAgentWithAReasoningModelAndToolsAsync()
+    {
+        // Define the agent
+        OpenAIResponseAgent agent = new(this.Client)
+        {
+            Name = "ResponseAgent",
+            Instructions = "Answer all queries with a detailed response.",
+        };
+
+        // Create a plugin that defines the tools to be used by the agent.
+        KernelPlugin plugin = KernelPluginFactory.CreateFromType<MenuPlugin>();
+        agent.Kernel.Plugins.Add(plugin);
+
+        // Invoke the agent and output the response
+        var responseItems = agent.InvokeAsync("What is the best value healthy meal?");
+        await foreach (ChatMessageContent responseItem in responseItems)
+        {
+            WriteAgentChatMessage(responseItem);
+        }
+    }
 }

dotnet/src/Agents/OpenAI/Internal/ResponseThreadActions.cs

@@ -57,7 +57,9 @@ internal static async IAsyncEnumerable<ChatMessageContent> InvokeAsync(
             }
             else
             {
-                inputItems.AddRange(response.OutputItems);
+                var filteredItems = response.OutputItems
+                    .Where(item => item is not ReasoningResponseItem); // Keep items that are not ReasoningResponseItem  
+                inputItems.AddRange(filteredItems);
             }
 
             var message = response.ToChatMessageContent();