Resolve CE-2233 Fix sx prop on KeyValueTable
- Fixes how the sx prop is used on KeyValueTable so that e.g. using the sx prop doesn't break/overwrite the "overline" variant
- Adds storybook stories demonstrating customization via sx prop
- adds SkeletonProps so that loading skeleton can be customized (in this case, making it a little taller in the "overline" variant to be consistent with the "table" variant)
- adds PropTypes to KeyValueTable
Closes CE-2233
Edited by Christina Jenks