feat(card): Set default color of card icons

[moterink]

Pull Request

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Type of PR

Feature (non-breaking change which adds functionality)

Checklist

• [x] I have read the CONTRIBUTING doc and I follow the PR guidelines
• [x] Lint and unit tests pass locally with my changes
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] I have added necessary documentation (if appropriate)

Changes

The default color of card icons is now $gray-700 (like default background for e.g. tile icons). Before there was no default color for card icons, so they were displayed as black unless the user explicitly specified a color.