Fix icon colors to be consistent across all sizes

Change the colors of icons that have had differing colors at certain sizes, to make them all consistent.

This MR will change:

• folder-important at size 48 & 96 to a red color (and add some presumably missing fill-rule attributes to 96),
• folder-paint at size 22 to same as text color,
• Godot mimetypes (except gdscript) at sizes 32 & 64 to their respective colors,
• RData mimetype at size 16 to the color used at all other sizes.

Screenshots (slightly jumbled, but should suffice)