Fix Color build

[Striffly]

This PR addresses issues in the build process of the Fluent UI Emoji project. It introduces support for color builds.

The font is correctly generated, however there is some issues remaining :

• the font does not contains any colors
  • Maybe because of this : colour font possible? nfroidure/svgicons2svgfont#163)
  • Maybe (maybe !) also related to COLR support : https://learn.microsoft.com/fr-fr/typography/opentype/spec/colr (I did not go into detail on the subject)
• also, font glyphs do not have the same width/height as the original SVG (valid for every glyphs variations)

[thejupitergroup]

@Striffly When we tried to build the fonts with your new code, the colors still don't show.

[Striffly]

@thejupitergroup Yes I know, this is part of the remaining bugs that I mentioned in the comment associated with my PR. The goal of this PR is to allow the build of the font with the Color variation (which wasn't possible before), but there is still a lot to do.