feat: Icon Component 2.0 (#4331)

* feat: icon 2.0 wip

* feat(icon): improve Icon 2.0 CSS and stories

- Add context-aware margins (Typography vs fallback)
- Simplify CSS with local variables for DRY code
- Update stories with Typography component
- Fix alignment in flex layouts

* docs: fix story

* docs: add story for combining size and modes

* feat(icon): fix sizing and simplify CSS

- Use font-size for icon sizing, width/height as 1em
- Unified margins for both fallback and Typography contexts
- Add TypographyWithDensity story
- Fix flex alignment in InlineWithText story

* test: ✅ Add tests for Icon

* test: ✅ Fix test

Author: pomfrida