Fix AddonLifecycle OnSetup hook (#1860)

* Fix AddonLifecycle OnSetup hook

* Fix namespace of AddonSetupHook

Dalamud/Game/Addon/Lifecycle/AddonSetupHook.cs

@@ -0,0 +1,80 @@
+using System.Runtime.InteropServices;
+
+using Reloaded.Hooks.Definitions;
+
+namespace Dalamud.Game.Addon.Lifecycle;
+
+/// <summary>
+/// This class represents a callsite hook used to replace the address of the OnSetup function in r9.
+/// </summary>
+/// <typeparam name="T">Delegate signature for this hook.</typeparam>
+internal class AddonSetupHook<T> : IDisposable where T : Delegate
+{
+    private readonly Reloaded.Hooks.AsmHook asmHook;
+    
+    private T? detour;
+    private bool activated;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="AddonSetupHook{T}"/> class.
+    /// </summary>
+    /// <param name="address">Address of the instruction to replace.</param>
+    /// <param name="detour">Delegate to invoke.</param>
+    internal AddonSetupHook(nint address, T detour)
+    {
+        this.detour = detour;
+
+        var detourPtr = Marshal.GetFunctionPointerForDelegate(this.detour);
+        var code = new[]
+        {
+            "use64",
+            $"mov r9, 0x{detourPtr:X8}",
+        };
+        
+        var opt = new AsmHookOptions
+        {
+            PreferRelativeJump = true,
+            Behaviour = Reloaded.Hooks.Definitions.Enums.AsmHookBehaviour.DoNotExecuteOriginal,
+            MaxOpcodeSize = 5,
+        };
+        
+        this.asmHook = new Reloaded.Hooks.AsmHook(code, (nuint)address, opt);
+    }
+
+    /// <summary>
+    /// Gets a value indicating whether or not the hook is enabled.
+    /// </summary>
+    public bool IsEnabled => this.asmHook.IsEnabled;
+    
+    /// <summary>
+    /// Starts intercepting a call to the function.
+    /// </summary>
+    public void Enable()
+    {
+        if (!this.activated)
+        {
+            this.activated = true;
+            this.asmHook.Activate();
+            return;
+        }
+        
+        this.asmHook.Enable();
+    }
+
+    /// <summary>
+    /// Stops intercepting a call to the function.
+    /// </summary>
+    public void Disable()
+    {
+        this.asmHook.Disable();
+    }
+
+    /// <summary>
+    /// Remove a hook from the current process.
+    /// </summary>
+    public void Dispose()
+    {
+        this.asmHook.Disable();
+        this.detour = null;
+    }
+}