fix: tup 730 news drop cap should work even if no caption (#864)

* fix: TUP-730 undo drop-cap more carefully

- undo ANY `p::first-letter`
- EXCEPT a `p.s-drop-cap`[^1]

[^1]: Added via snippet. To be added via Core-Styles.

* feat: TUP-730 allow drop-cap if no caption

* feat: TUP-730 core-styles v2.31.0

* fix: TUP-730 remove drop-cap edge case

Author: wesleyboar