Introduce emptyWhileLoading on <ListBase>

[djhi]

Problem

When using iterator like components as direct children of ListBase, they have to check the isPending state.

Solution

• Introduce emptyWhileLoading on <ListBase> so they don't have to.
• Also fix offine tests impacting other tests

How To Test

• Story With Children
• Story With render prop
• Unit tests

Additional Checks

• The PR targets master for a bugfix or a documentation fix, or next for a feature
• The PR includes unit tests (if not possible, describe why)
• The PR includes one or several stories (if not possible, describe why)
• The documentation is up to date

Also, please make sure to read the contributing guidelines.