[sfnt] Add API to retrieve 'COLR' v1 root paint (#59703).

* src/sfnt/ttcolr.c (BaseGlyphV1Record): New structure.
(tt_face_load_colr): Handle version 1 table header.
(find_base_glyph_v1_record): New auxiliary function.
(tt_face_get_colr_glyph_paint): New function to find the root
`FT_OpaquePaint` object for a given glyph ID.

* src/sfnt/ttcolr.h: Updated.
3 files changed