Rebased and adopted from #5774 by @felixturner.
## Changes
- Remove unused font-size properties (`NODE_TEXT_SIZE`,
`NODE_SUBTEXT_SIZE`, `DEFAULT_GROUP_FONT`) from theme palettes and color
palette schema
- Replace `DEFAULT_GROUP_FONT`/`DEFAULT_GROUP_FONT_SIZE` with a single
`GROUP_TEXT_SIZE = 20` constant (reduced from 24px)
- Use `NODE_TITLE_HEIGHT` for group header height instead of `font_size
* 1.4`
- Vertically center group title text using `textBaseline = 'middle'`
- Use `GROUP_TEXT_SIZE` directly in TitleEditor instead of per-group
`font_size`
- Remove `font_size` from group serialization (no longer per-group
configurable)
## Original PR
Closes#5774
┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-9839-feat-Improve-group-title-layout-3216d73d36508112a0edc2a370af20ba)
by [Unito](https://www.unito.io)
---------
Co-authored-by: Felix Turner <felixturner@gmail.com>
Co-authored-by: github-actions <github-actions@github.com>
Co-authored-by: Alexander Brown <drjkl@comfy.org>
