Introduce static resource URLs

Summary: Introduced an API that converts a filepath, relatively to the `desktop/static/` folder in a url that can be resolved by the render environment. This will generate `file://` urls in Electron, and root relative `/` urls in browser envs

Reviewed By: aigoncharov

Differential Revision: D32767427

fbshipit-source-id: 378da7709bcb19449873358a8703b9c5a5809c57

desktop/app/src/electron/initializeElectron.tsx

@@ -180,6 +180,12 @@ export function initializeElectron(
     async requirePlugin(path) {
       return (window as any).electronRequire(path);
     },
+    getStaticResourceUrl(relativePath): string {
+      return (
+        'file://' +
+        path.resolve(flipperServerConfig.paths.staticPath, relativePath)
+      );
+    },
   } as RenderHost;
 
   setupMenuBar();