Initial migration commit to .NET 7

Menu, sync and other stuff except resource system should be working.
We're far from finished

Client/Scripts/ThreadManager.cs

@@ -0,0 +1,77 @@
+using RageCoop.Client.Scripting;
+using RageCoop.Core;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading;
+
+namespace RageCoop.Client
+{
+
+    /// <summary>
+    /// Needed to properly stop all thread when the module unloads
+    /// </summary>
+    internal static class ThreadManager
+    {
+        private static List<Thread> _threads = new();
+        private static Thread _watcher = new(() => _removeStopped());
+        private static void _removeStopped()
+        {
+            while (!Main.IsUnloading)
+            {
+                lock (_threads)
+                {
+                    _threads.RemoveAll(t => !t.IsAlive);
+                }
+                Thread.Sleep(1000);
+            }
+        }
+        public static Thread CreateThread(Action callback, string name = "CoopThread", bool startNow = true)
+        {
+            lock (_threads)
+            {
+                var created = new Thread(() =>
+                {
+                    try
+                    {
+                        callback();
+                    }
+                    catch (ThreadInterruptedException) { }
+                    catch (Exception ex)
+                    {
+                        Main.Logger.Error($"Unhandled exception caught in thread {Environment.CurrentManagedThreadId}", ex);
+                    }
+                    finally
+                    {
+                        Main.Logger.Debug($"Thread stopped: " + Environment.CurrentManagedThreadId);
+                    }
+                });
+                created.Name = name;
+                Main.Logger.Debug($"Thread created: {name}, id: {created.ManagedThreadId}");
+                _threads.Add(created);
+                if (startNow) created.Start();
+                return created;
+            }
+        }
+
+        public static void OnUnload()
+        {
+            lock (_threads)
+            {
+                foreach (var thread in _threads)
+                {
+                    if (thread.IsAlive)
+                    {
+                        Main.Logger.Debug($"Waiting for thread {thread.ManagedThreadId} to stop");
+                        // thread.Interrupt(); PlatformNotSupportedException ?
+                        thread.Join();
+                    }
+                }
+                _threads.Clear();
+                _threads = null;
+                _watcher.Join();
+            }
+        }
+    }
+}