Add message acknowledgement

The bot can acknowledge a message by reacting with ✅

This provides the caller some feedback that the bot is indeed running, and a lack of response may be down to erroneous code

Hammer/Extensions/CommandContextExtensions.cs

@@ -0,0 +1,18 @@
+using DisCatSharp.CommandsNext;
+
+namespace Hammer.Extensions;
+
+/// <summary>
+///     Extension methods for <see cref="CommandContext" />.
+/// </summary>
+internal static class CommandContextExtensions
+{
+    /// <summary>
+    ///     Acknowledges the message provided by a <see cref="CommandContext" /> by reacting to it.
+    /// </summary>
+    /// <param name="context">The command context.</param>
+    public static Task AcknowledgeAsync(this CommandContext context)
+    {
+        return context.Message.AcknowledgeAsync();
+    }
+}

Hammer/Extensions/DiscordMessageExtensions.cs

@@ -0,0 +1,18 @@
+using DisCatSharp.Entities;
+
+namespace Hammer.Extensions;
+
+/// <summary>
+///     Extension methods for <see cref="DiscordMessage" />.
+/// </summary>
+internal static class DiscordMessageExtensions
+{
+    /// <summary>
+    ///     Acknowledges a message by reacting to it.
+    /// </summary>
+    /// <param name="message">The message to acknowledge.</param>
+    public static Task AcknowledgeAsync(this DiscordMessage message)
+    {
+        return message.CreateReactionAsync(DiscordEmoji.FromUnicode("✅"));
+    }
+}