Styles for mw-ui-icon are inconsistent with Codex. We can update these now with no need for a feature flag.
TODO
We will align the following:
- Align Hover background colors (Core change)
- Align Icon glyph colors to #222 (Vector change)
QA
- Verify that the columns in https://doc.wikimedia.org/mediawiki-skins-Vector/master/js/ui/?path=/story/icon-and-buttons--button show identical button/icons (with caveats that Codex's icon/label alignment is different and Codex doesn't have small icon buttons and icons can vary in color since Codex uses an embedded and updated SVG)