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

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

src-electron/preload.js

@@ -39,9 +39,7 @@ contextBridge.exposeInMainWorld('electron', {
     desktopNotification: (title, body, icon) =>
         ipcRenderer.invoke('notification:showNotification', title, body, icon),
     restartApp: () => ipcRenderer.invoke('app:restart'),
-    getWristOverlayWindow: () =>
-        ipcRenderer.invoke('app:getWristOverlayWindow'),
-    getHmdOverlayWindow: () => ipcRenderer.invoke('app:getHmdOverlayWindow'),
+    getOverlayWindow: () => ipcRenderer.invoke('app:getOverlayWindow'),
     updateVr: (active, hmdOverlay, wristOverlay, menuButton, overlayHand) =>
         ipcRenderer.invoke(
             'app:updateVr',