This is in preparation of larger change of moving CollapsingTextHelper onto TextAppearance to fix related bugs & avoid code duplication.
1. Introduces a version of getFontAsync() in TextAppearance that doesn't require TextPaint as an argument.
2. Refactors the existing getFontAsync to wrap the new implementation.
3. Fixes a bug - TextAppearance would not apply the correct typeface from a style when fontFamily was not present in the style def.
PiperOrigin-RevId: 209147825
