message: fix(side-nav): fix icon color
  Fixes icon color in `<bx-side-nav-link>` by explicitly setting the
  color.
  Refs
diff: @@ -59,10 +59,14 @@ $css--plex: true !default;
  width: auto;
  height: auto;
  - .#{$prefix}--side-nav__icon[hidden] {
  + .#{$prefix}--side-nav__icon {
  + color: $shell-side-nav-text-01;
  +
  + &[hidden] {
  display: none;
  }
  }
  +}
  :host(#{$prefix}-side-nav-menu) {
  @extend .#{$prefix}--side-nav__item;
  