[Task](ui): unify default padding strategy across our components

[franzheidl]

Currently, our components use different padding (default) strategies: Some compients come with default padding, some expose an unpad prop to remove it, some may use other mechanisms.

In order to provide a consistent, more predictable and easier-to-learn and -remember interface, we should unify our approach as well as the values we actually use.

• find all components that use unpad (and components that call unpad on a child / subcomponent internally), and replace with padding and the respective boolean or numerical value
• document that strategy in our uxdocs
• update stories that use this

Depends on #1641