Add ServiceLocator so patches can access DI

Libraries/SPTarkov.Server.Core/DI/ServiceLocator.cs

@@ -0,0 +1,22 @@
+namespace SPTarkov.Server.Core.DI
+{
+    /// <summary>
+    /// A service locator designed specifically for Harmony patches and other 
+    /// parts of the application that do not have direct access to the Dependency Injection (DI) system.
+    ///
+    /// This should not be used at all when having direct access to DI.
+    /// </summary>
+    public static class ServiceLocator
+    {
+        public static IServiceProvider ServiceProvider
+        {
+            get;
+            private set;
+        }
+
+        internal static void SetServiceProvider(IServiceProvider provider)
+        {
+            ServiceProvider = provider;
+        }
+    }
+}

Libraries/SPTarkov.Server.Core/Utils/App.cs

@@ -11,6 +11,7 @@ namespace SPTarkov.Server.Core.Utils;
 
 [Injectable(InjectionType.Singleton)]
 public class App(
+    IServiceProvider _serviceProvider,
     ISptLogger<App> _logger,
     TimeUtil _timeUtil,
     RandomUtil _randomUtil,
@@ -30,6 +31,8 @@ public class App(
 
     public async Task InitializeAsync()
     {
+        ServiceLocator.SetServiceProvider(_serviceProvider);
+
         // execute onLoad callbacks
         _logger.Info(_localisationService.GetText("executing_startup_callbacks"));