Feature: Checkbox/Radiobutton with bold example

[kyubisation]

For specific use cases a checkbox/radio button with bold text is needed. This is already possible to do with the CSS class sbb-text--bold.

Add a story with the following example:

<sbb-checkbox>
  <span class="sbb-text--bold">Bold Label</span>
</sbb-checkbox>

Add a story with the following example:

<sbb-radio-button>
  <span class="sbb-text--bold">Bold Label</span>
</sbb-radio-button>

Needed for ÖVG:
https://www.figma.com/file/BS4MP1EC7Fb22MgcWtwlOX/07%3A-Design-%E2%80%93-%C3%96V-Guthaben?type=design&node-id=9425-785431&t=HahdDz3Wy73Beksr-0