Shareable web baseline (ours) config

[phndiaye]

What does this PR do?

This PR adds a shared browserslist with what we considering our safe Web Baseline, targeting the mid-2022 era.

Went from the browsers we used to support already (Chrome, Safari, Firefox) and just added Edge. With the specifiers being available in: https://github.com/browserslist/browserslist/blob/main/grammar.w3c-ebnf#L9-L39.

It's intended to be used in Ember config/target.js files.

What are the observable changes?

Good PR checklist

• Title makes sense
• Is against the correct branch
• Only addresses one issue
• Properly assigned
• Added/updated tests
• Added/updated documentation
• Properly labeled

[phndiaye]

Discussed w/ @edouardmisset:

• (P1) Move to baseline widely available with downstream instead of exact list and delegate to Browserslist
  • This means mainly update browserslsit everywhere
  • Confirm browsers coverage (one shot) + Confirm w/ CS/Product team.
• (P2) Automate browserslists update via cronjob
  • To go with it, find a way to automatically get the stats from Analytics to prove that a browserslists update still fits into our traffic stats (maybe linting step in the CI ???)
  • Define a safety percentage coverage

[edouardmisset]

question: Also I feel like the config you implemented is specifically targeting ember's ecosystem (which is not a problem). I kind of assumed that the scope of browserslist should go beyond to our more general tooling as well. What do you think? Maybe this is step 1 of... ?

[phndiaye]

It is (bound to Ember for now) considering we have to go through the Ember compat anyway :)

But it's only a start and can evolve. However, considering not all tools are configured the same way (For example, eslint-plugin-compat only supporting configuration through the package.json — from their README at least), I think we might need multiple ways input this config to tools. browsers dir could have other files fitted more for other tools maybe? 🤔

[edouardmisset]

yep sounds good. 🙏

The only thing on which I will want to highlight is the fact that we should only have a single source of truth and derive the others from it.

I'm thinking about a single JS file and a script (automatically run; when?) that generates/derives the other files/format needed