[ISO] Add 24bit-GID Paints to `COLR` table

[behdad]

Similar to: https://learn.microsoft.com/en-us/typography/opentype/spec/colr#format-10-paintglyph

struct PaintGlyph2
{
  uint8 format; // 33
  Offset24 paintOffset;
  uint24 glyphID;
};

Similar to https://learn.microsoft.com/en-us/typography/opentype/spec/colr#format-11-paintcolrglyph

struct PaintGlyph2
{
  uint8 format; // 34
  uint24 glyphID;
};

Search over the text for PaintGlyph and PaintColrGlyph and update as needed.

@PeterCon I can also add format 3/4 of ClipBoxList to extend to 24bit GIDs. Should I do that?

[behdad]

@PeterCon I can also add format 3/4 of ClipBoxList to extend to 24bit GIDs. Should I do that?

Nevermind. BaseGlyphPaintRecord is still gid16.

[liamquin]

Added PaintGlyph2 and PaintColrGlyph2, and updated sections that mention either of them, where it seemed useful or necessary.