Update recommended version to Node.js 18 (#1117)

After #1115, new Node.js versions will be able to be used for
development of the frontend. This PR changes the recommended Node.js
version to 18 (the current LTS version). I have also tested with 16 and
20 and it works.

I also took the opportunity to:

- move the build script that was at the project root to the `bin/`
folder
- update the `browserslist` to target Electron 24 (which is the version
we currently build against). This results in a slightly smaller bundle
due to no longer having to transpile optional chaining.

package.json

@@ -53,9 +53,12 @@
   "resolutions": {
     "react-error-overlay": "6.0.9"
   },
+  "engines": {
+    "node": ">=18.0.0"
+  },
   "packageManager": "yarn@3.5.1",
   "browserslist": [
-    "electron 12.0",
+    "electron 24.0",
     "defaults"
   ]
 }