[KOA-6229] Add viewbox to all JS icons and spinners

[anambl]

In order for SVGs to scale, we need to add a viewBox attribute. Due to an issue with svgo library, the removeViewBox plugin which is enabled by default cannot be disabled. This plugin only runs if the viewBox width and height values are equal to the width and height attributes on the svg and so one solution is to remove the width and height attributes altogether. We are still using the style attribute to set the width and height so it should not have any impact visually.

Changes:

• Remove width and height attributes from all JS icons
• Add viewBox attribute to all LG icons (SM icons already have a viewBox)
• Add viewBox and style to all JS spinners
• Replace width and height attributes on SVG spinners with viewBox (this matches all SVG icons)

Remember to include the following changes:

• UNRELEASED.md (See How to write a good changelog entry)
• README.md
• Tests
• Storybook examples created/updated for changes to tokens, mixins, icons

[anambl]

I don't know why this exists, but it is not used anywhere.