Webpack: move Twemoji icons back to CopyPlugin

app/soapbox/utils/static.js

@@ -0,0 +1,11 @@
+/**
+ * Static: functions related to static files.
+ * @module soapbox/utils/static
+ */
+
+import { join } from 'path';
+import { FE_SUBDIRECTORY } from 'soapbox/build_config';
+
+export const joinPublicPath = (...paths) => {
+  return join(FE_SUBDIRECTORY, ...paths);
+};