Update the yargs package to the latest version

While I wasn't able to figure out *exactly* why the old format didn't work, re-factoring the `parseOptions` function to use `yargs` differently "just worked" so that's hopefully good enough here.
With these changes everything related to a *particular* option now appears in one place, rather than being spread out, which aids readability in my opinion. Also, the options are now sorted alphabetically, to make it easier to find a particular one.

https://www.npmjs.com/package/yargs

package.json

@@ -60,7 +60,7 @@
     "webpack": "^5.30.0",
     "webpack-stream": "^6.1.2",
     "wintersmith": "^2.5.0",
-    "yargs": "^11.1.1"
+    "yargs": "^16.2.0"
   },
   "scripts": {
     "postinstall": "cross-env PUPPETEER_PRODUCT=firefox node node_modules/puppeteer/install.js",