story(scss): mixins for onetrust cookie conset banner

[kyubisation]

Feature Description

sbb.ch/WebEx have the requirement to align the design of the onetrust cookie consent banner.
To enable this, mixins for button (❌), link (✔️), title (✔️), copy (✔️), expansion panel (❌), dialog (❌, outer shell) and toggle check (❌, will be applied to a label element) are needed.

With this story it should be evaluated, how we can provide scss mixins for WebEx to use for this requirement.
Additionally, it should be decided whether these mixins should be fully documented or provided as a hidden feature.

To see the cookie consent banner, open https://www.sbb.ch/ in incognito mode.
Figma: https://www.figma.com/file/0bciMREs4pYK7z6jGqZ3RE/01%3A-Design-%E2%80%93-Home-2.0?type=design&node-id=12854-274013&mode=design&t=6VBEKtiyO8piHopH-0 (Cookie list is out of scope)

The potential markup can be seen on www.sbb.ch when the consent banner is displayed (use private tab). For the expansion panel you have to click on "Show purposes".

Definition of Done

• Button mixin implemented
• Expansion panel mixin implemented
• Dialog (outer shell) mixin implemented
• Toggle check mixin implemented
• Documentation is provided (To decide)
• Storybook stories are implemented (To decide)
• High-contrast is tested

[jeripeierSBB]

After some research my personal opinion:

• Button should be possible to provide as mixin
• Toggle check will be difficult to apply to the structure of the Onetrust consent (completely different structure).
• Expansion Panel is difficult too, maybe possible.
• For the dialog I'm tending to not partially extract it, as it should have the design of a sheet anyway and is probably easier to be built from scratch on WebEx side.