Allow viewing Flash posts with the Ruffle emulator. Known issues: * Many flash files aren't fully supported. * In development it sometimes spazzes out and starts triggering random keyboard shortcuts when you press any key. This doesn't happen with the browser extension. * We have to put the .wasm file in the public/packs/js directory because Ruffle is hardcoded to search for it there. * If you're running Nginx, you need to make sure you're serving the right MIME type for .wasm files or it won't work. * We're using Some Random Guy's unofficial NPM package for Ruffle, since the Ruffle project doesn't publish an official package themselves. We should build our own package. References: * https://github.com/ruffle-rs/ruffle * https://github.com/ruffle-rs/ruffle/wiki/Using-Ruffle#configure-webassembly-mime-type * https://www.npmjs.com/package/ruffle-mirror