Improve SVG color map handling.

[bruvzg]

Fixes godotengine/godot-proposals#14910

Adds handing for name:xxx; values in addition to name="xxx" as well as rgb()/rgba()/hsl()/hsla() CSS colors.

[MewPurPur]

Sounds good. I saw that the code expanded the list of attributes. While at it, we can also include the color and lightning-color attributes (e.g., https://developer.mozilla.org/en-US/docs/Web/SVG/Reference/Attribute/color) to complete the list.

Idk if ThorVG supports lightning-color, but it definitely supports color.

[bruvzg]

While at it, we can also include the color and lightning-color attributes

Updated. It's prefix, so simply using color should cover all *color cases.

[MewPurPur]

Hmm... I don't know about that, suffix matching seems dangerous and like it could risk mutating unrelated metadata (e.g. <metadata inkscape-canvas-color="#decade"/> or something). My intuition says you should only match these 6 exact attribute names.

[bruvzg]

e.g. or something

Does it matter, it's only applied before the rendering, and metadata like this should be ignored.

[MewPurPur]

Oh, you're right, my bad, since this is only for rendering, I can't think of situations where it'd matter.