Add AddonLifecycle Service (#1361)

Adds new service to manage addon lifecycle events, such as setup/teardown.

Dalamud/Plugin/Services/IAddonLifecycle.cs

@@ -0,0 +1,50 @@
+using System;
+
+using Dalamud.Memory;
+using FFXIVClientStructs.FFXIV.Component.GUI;
+
+namespace Dalamud.Plugin.Services;
+
+/// <summary>
+/// This class provides events for in-game addon lifecycles.
+/// </summary>
+public interface IAddonLifecycle
+{
+    /// <summary>
+    /// Event that fires before an addon is being setup.
+    /// </summary>
+    public event Action<AddonArgs> AddonPreSetup;
+    
+    /// <summary>
+    /// Event that fires after an addon is done being setup.
+    /// </summary>
+    public event Action<AddonArgs> AddonPostSetup;
+    
+    /// <summary>
+    /// Event that fires before an addon is being finalized.
+    /// </summary>
+    public event Action<AddonArgs> AddonPreFinalize;
+    
+    /// <summary>
+    /// Event that fires after an addon is done being finalized.
+    /// </summary>
+    public event Action<AddonArgs> AddonPostFinalize;
+    
+    /// <summary>
+    /// Addon argument data for use in event subscribers.
+    /// </summary>
+    public unsafe class AddonArgs
+    {
+        private string? addonName;
+        
+        /// <summary>
+        /// Gets the name of the addon this args referrers to.
+        /// </summary>
+        public string AddonName => this.addonName ??= MemoryHelper.ReadString((nint)((AtkUnitBase*)this.Addon)->Name, 0x20);
+
+        /// <summary>
+        /// Gets the pointer to the addons AtkUnitBase.
+        /// </summary>
+        required public nint Addon { get; init; }
+    }
+}