Enhance prettier and format more code

[jooola]

Requires #82 to be merged first.

This PR is part of the big #83 plan.

[nopeless]

Consider dropping 4660f21
and a3426fb

and let repo owner push these refactor commits

[elliotblackburn]

I've pulled in #82 after what has been way too long, lets be honest 😅. What I've done with this PR is cherry pick a few commits into master directly. There are a couple reasons for this:

1. I'd rather not do a full prettier run on the entire project, I know it's been lax and it does need sorting but I want to get all open PR's triaged before pushing that change as it would cause a lot of merge conflicts.
2. I've made a few edits to the prettier setup. I'd rather we didn't run it on the css because that's generated by extracting it github's markdown rendering css. While formatting it wouldn't be terrible it will make things harder to diff in the future if we need to do an update.

I've cherry picked the prettierrc change and the dev dependecy ones over and merged those together. @jooola apologies this has taken so long, I don't really work with nodejs much anymore so this project has fallen off my priority list over the last few years. Thanks so much for your contribution though, it'll be in the next release and is on master now 🚀

Better late than never? 😆

[jooola]

All good ! Better late than never !