feat: action mixin

[wesleyboar]

Overview / Changes

Add action mixin. (Actions are buttons and links.) Its only styles are related to icons within an action.

Related

• required by feat: c-feed-list #508
• coupled with fix: action mixin #512

Testing

1. Review http://localhost:3000/components/detail/x-action.
2. Check alignment of icons in actions on http://localhost:3000/components/detail/c-card.

UI

action mixin

x-action

c-card action

icon in action link in paragraph	icon in action link as direct child	icon in action button