Library: Fix components preview (2/2)

Added library_wrapper key in stories for above components:

• code (code.default.story.yml)
• modal (modal.default.story.yml)
• step (step.default.story.yml)
• tab (tab.default.story.yml)
• table_cell/table_cell.default.story.yml)
• timeline_item (timeline_item.default.story.yml)
• toast (toast.default.story.yml)