Add command to serve production build (#352)

I use this command to debug a production build more quickly

Author: 2xic

package.json

@@ -9,6 +9,7 @@
     "build:solcjs-worker": "npx -y browserify -t babelify ./babel/solcWorker2.js > ./public/solcWorker.js",
     "dev": "pnpm run build:solcjs-worker && next dev",
     "format": "prettier --write  --cache .",
+    "serve": "pnpm run build && next start",
     "preinstall": "git submodule update --init",
     "postinstall": "./setup_monorepo.sh",
     "lint": "eslint --ext js,jsx,ts,tsx .",