story(sbb-mini-button-group): initial implementation

[mcilurzo]

We want to provide a mini-button-group component.
It's purpose is to provide a list of actions.

Figma: https://www.figma.com/design/9r6xSfNmEfCFxl1yFYedrj/Lyne-Components?m=auto&node-id=32457-650777&t=bsLmIu6BsmRYYOZV-1

Design Spec:

• Should display a list of buttons horizontally
• Should not break/wrap

Tech Spec:

• Should be implemented as a list component (If a more appropriate aria pattern is discovered, discuss it in plenum)
• Should not use sbb-divider, just css for the separators between buttons
• The list title (aria-label) should probably be set by a property for accessibility reasons.
• Navigation between buttons only via tab and not via arrows (keep it simple).

<sbb-mini-button-group>
  <sbb-mini-button>Action 1</sbb-mini-button>
  <sbb-mini-button>Action 2</sbb-mini-button>
</sbb-mini-button-group>

<sbb-mini-button-group>
  <sbb-mini-button>Action 1</sbb-mini-button>
  <sbb-divider></sbb-divider>
  <sbb-mini-button>Action 2</sbb-mini-button>
</sbb-mini-button-group>