Closes #32424

This PR fixes two bugs:

* In cases like `fi ~~something~~`, the `fi` gets rendered as a
ligature, meaning the two characters are combined into a single glyph.
The final glyph index didn’t account for this change, which caused
issues.
* On Windows, some emojis are composed of multiple glyphs. These
composite emojis can now be rendered correctly as well.

![屏幕截图 2025-06-22
161900](https://github.com/user-attachments/assets/e125426b-a15e-41d1-a6e6-403a16924ada)

![屏幕截图 2025-06-22
162005](https://github.com/user-attachments/assets/f5f01022-2404-4e73-89e5-1aaddf7419d9)


Release Notes:

- N/A