Use @brandFontName for brand icon's font-family CSS rule

[lolero]

Bug Report

The @brandFontName variable is not consumed in icon.overrides as it should be.

Steps

I have an open PR with the fix.

Expected Result

If I want to use different icon libraries aside from those offered by SUI, overriding the @brandFontName variable should render the icons that I want.

Actual Result

Overriding the @brandFontName variable does not render my third-party icons.