.NET: Durable Agent samples and automated validation for non-Azure Functions (#3042)

* Durable Agent samples and automated validation for non-Azure Functions

* Update test projects

* fix file encoding

* Remove AgentThreadMetadata usage

* Absorb breaking change from #3152

* Absorb newer breaking changes (AgentRunResponse --> AgentResponse)

* Absorb more breaking changes (see #3222)

* Improve integration test reliability (isolated task hubs, etc.)

* Fix flakey streaming test

---------

Co-authored-by: Mark Wallace <127216156+markwallace-microsoft@users.noreply.github.com>

dotnet/samples/DurableAgents/ConsoleApps/06_LongRunningTools/Models.cs

@@ -0,0 +1,44 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System.Text.Json.Serialization;
+
+namespace LongRunningTools;
+
+/// <summary>
+/// Represents the input for the content generation workflow.
+/// </summary>
+public sealed class ContentGenerationInput
+{
+    [JsonPropertyName("topic")]
+    public string Topic { get; set; } = string.Empty;
+
+    [JsonPropertyName("max_review_attempts")]
+    public int MaxReviewAttempts { get; set; } = 3;
+
+    [JsonPropertyName("approval_timeout_hours")]
+    public float ApprovalTimeoutHours { get; set; } = 72;
+}
+
+/// <summary>
+/// Represents the content generated by the writer agent.
+/// </summary>
+public sealed class GeneratedContent
+{
+    [JsonPropertyName("title")]
+    public string Title { get; set; } = string.Empty;
+
+    [JsonPropertyName("content")]
+    public string Content { get; set; } = string.Empty;
+}
+
+/// <summary>
+/// Represents the human feedback response.
+/// </summary>
+public sealed class HumanFeedbackResponse
+{
+    [JsonPropertyName("approved")]
+    public bool Approved { get; set; }
+
+    [JsonPropertyName("feedback")]
+    public string Feedback { get; set; } = string.Empty;
+}