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/OverlayMessageType.cs

@@ -0,0 +1,9 @@
+namespace VRCX;
+
+public enum OverlayMessageType
+{
+    OverlayConnected,
+    JsFunctionCall,
+    UpdateVars,
+    IsHmdAfk
+}