cosmic_text: Handle variation selectors; fix emoji colors

[apricotbucket28]

Basically, we detect if a glyph is a variation selector if its id is 3 (i.e. a whitespace character) and if it comes from an emoji font (since variation selectors are only used for emoji glyphs).

• Fixes Crash when typing b in css file #11703 and Linux. Crash when typing "--da" after having another CSS variable beginning with the same name #12022

Release Notes:

• N/A

[mikayla-maki]

Thank you!