Formalizing Icon Export Guidelines

[bennypowers]

Having discussed issues of decimal precision in SVG paths with @libbylevi and @markcaron , I wanted to formalize some guidelines around SVG export into the new red-hat-icons repo, when it will be ready to accept new content.

Here are my initial thoughts

• remove attributes
• remove unneccessary groups
• convert style to fill/attributes
• avoid fill attribute except for duotone variants
• don't minify whitespace
• simplify paths

These are IIRC all SVGO rules which we can probably prepare as presets for popular graphics editors, or as automations steps in this repo (e.g. github actions that lint and fix PRs which add or edit icons)

I'd also like remove the guideline to save separate colorways, and just have no-fill. build tooling can produce colour varieties (or we'd use rh-icon or currentColor on consuming pages)