Allow users to change asciidoctor-web-pdf's headless chrome to firefox.

[Robot-Nachos]

Discussed in #695

^{Originally posted by Robot-Nachos October 15, 2023}
Is it possible change out the headless chrome that asciidoctor-web-pdf uses for Firefox? I have a document that makes use of -webkit-text-stroke and paint-order is necessary to draw the outline behind the text, instead of in front of it. Chrome doesn't support paint-order for HTML text correctly, but Firefox does. I haven't had any luck faking similar results using text shadows or similar methods.

My understanding is that once you've enabled Firefox with PUPPETEER_PRODUCT=Firefox yarn add puppeteer you just need to add ({ product: 'firefox' }) after puppeteer.launch. I tried doing that in browser.js but it results in a timeout error from puppeteer.