Simplequeue improvements: dead letters and backoff policy (#827)

## Motivation and Context (Why the change? What's the scenario?)

When working with simplequeue locally, it's difficult to debug errors
missing some better pipeline retry logic.

## High level description (Approach, Design)

* Add poison message handling to SimpleQueue
* Add backoff policy to SimpleQueue

extensions/AzureQueues/AzureQueuesPipeline.cs

@@ -255,7 +255,7 @@ private void DispatchMessages(object? sender, ElapsedEventArgs ev)
         {
             this._busy = true;
 
-            QueueMessage[] messages = Array.Empty<QueueMessage>();
+            QueueMessage[] messages = [];
 
             // Fetch messages
             try

service/Core/FileSystem/DevTools/VolatileFileSystem.cs

@@ -367,7 +367,7 @@ private static string ValidateVolumeName(string volume)
 
         if (s_invalidCharsRegex.Match(volume).Success)
         {
-            throw new ArgumentException("The volume name contains some invalid chars or empty spaces");
+            throw new ArgumentException($"The volume name '{volume}' contains some invalid chars or empty spaces");
         }
 
         return volume;

service/Core/Pipeline/Queue/DevTools/Message.cs

@@ -0,0 +1,55 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System;
+using System.Text.Json.Serialization;
+
+namespace Microsoft.KernelMemory.Pipeline.Queue.DevTools;
+
+internal class Message
+{
+    [JsonPropertyName("id")]
+    public string Id { get; set; } = string.Empty;
+
+    [JsonPropertyName("content")]
+    public string Content { get; set; } = string.Empty;
+
+    [JsonPropertyName("deliveries")]
+    public uint DequeueCount { get; set; } = 0;
+
+    [JsonPropertyName("created")]
+    public DateTimeOffset Created { get; set; } = DateTimeOffset.UtcNow;
+
+    [JsonPropertyName("schedule")]
+    public DateTimeOffset Schedule { get; set; } = DateTimeOffset.UtcNow;
+
+    [JsonPropertyName("lock")]
+    public DateTimeOffset LockedUntil { get; set; } = DateTimeOffset.MinValue;
+
+    [JsonPropertyName("error")]
+    public string LastError { get; set; } = string.Empty;
+
+    public bool IsLocked()
+    {
+        return this.LockedUntil > DateTimeOffset.UtcNow;
+    }
+
+    public bool IsTimeToRun()
+    {
+        return this.Schedule <= DateTimeOffset.UtcNow;
+    }
+
+    public void RunIn(TimeSpan delay)
+    {
+        this.Schedule = DateTimeOffset.UtcNow + delay;
+    }
+
+    public void Lock(int seconds)
+    {
+        this.LockedUntil = DateTimeOffset.UtcNow + TimeSpan.FromSeconds(Math.Max(0, seconds));
+    }
+
+    public void Unlock()
+    {
+        this.LockedUntil = DateTimeOffset.MinValue;
+    }
+}