Color Setting for Icons

[gierens]

In the discussion https://github.com/orgs/eza-community/discussions/891 the user asks about the ability to make the icon color different from the file name color. I took a peek into the code and actually ended up implementing this functionality.

So this adds the EZA_COLORS variable ic for icon which ends up as an Option<Style> in the UiStyle with None as default. The logic in the FileName.paint is adjusted to apply the icon style when the value is Some and otherwise fall back to the usual behavior, namely that the icon color matches the file name color.