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/scripts/jest-setup-after.ts

@@ -187,5 +187,8 @@ function createStubRenderHost(): RenderHost {
     async requirePlugin(path: string) {
       return require(path);
     },
+    getStaticResourceUrl(relativePath): string {
+      return 'file://' + resolve(rootPath, 'static', relativePath);
+    },
   };
 }