Save as PDF from Right-Click / Context Menu per Will

With this extension installed, you can:

1. Right click any web page
2. Click "Save as PDF"
3. Choose where to download the web page as a PDF to your device

It uses the saveAsPDF function built into Firefox to save the PDF. The saveAsPDF function is documented here: https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/tabs/saveAsPDF