Merge overlays, move overlay to separate process (#44)

* refactor: merge two overlay offScreenBrowser into one

* Electron support for shared overlay

* Separate overlay into its own process

* fix: invalid overlay texture size

* Handle duplicate processes

* Remove logging

---------

Co-authored-by: pa <maplenagisa@gmail.com>
Co-authored-by: rs189 <35667100+rs189@users.noreply.github.com>

Dotnet/OverlayWebSocket/OverlayManager.cs

@@ -0,0 +1,53 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.IO;
+using NLog;
+
+namespace VRCX;
+
+public class OverlayManager
+{
+    private static readonly Logger logger = LogManager.GetCurrentClassLogger();
+    
+    private static Process _process;
+
+    public static void StartOverlay()
+    {
+        if (OverlayServer.IsConnected() ||
+            _process != null && !_process.HasExited)
+        {
+            logger.Error("Overlay server already started");
+            return;
+        }
+
+        StartOverlayProcess();
+    }
+    
+    private static void StartOverlayProcess()
+    {
+        if (Environment.ProcessPath == null)
+        {
+            logger.Error("Cannot start Overlay process without a process path");
+            return;
+        }
+        
+        var args = new List<string>();
+        args.Add(StartupArgs.VrcxLaunchArguments.Overlay);
+        if (Program.LaunchDebug)
+            args.Add(StartupArgs.VrcxLaunchArguments.IsDebugPrefix);
+        if (StartupArgs.LaunchArguments.ConfigDirectory != null)
+            args.Add($"{StartupArgs.VrcxLaunchArguments.ConfigDirectoryPrefix}={StartupArgs.LaunchArguments.ConfigDirectory}");
+
+        var startInfo = new ProcessStartInfo
+        {
+            FileName = Environment.ProcessPath,
+            Arguments = string.Join(' ', args),
+            UseShellExecute = false,
+            CreateNoWindow = true,
+            WorkingDirectory = Program.BaseDirectory
+        };
+        _process = Process.Start(startInfo);
+        logger.Info("Overlay process started");
+    }
+}