feat(ExpandableSection): functional toggleContent

[gitdallas]

What: Closes #12030

[patternfly-build]

Preview: https://pf-react-pr-12063.surge.sh

A11y report: https://pf-react-pr-12063-a11y.surge.sh

[thatblindgeye]

This lgtm, especially as a means to set the toggle content for controlled or uncontrolled implementations.

I think ultimately maybe it depends what we want the API to look like in the future:

• Would we want to have the API set in such a wway that a consumer only needs to pass toggleContent, and we remove toggleText, toggleTextExpanded, and toggleTextCollapsed? One prop to rule them all etc
• Or would we want a prop intended for a controlled implementation (toggleContent), and have 2 props for uncontrolled implementations (replacing toggleTextExpanded and toggleTextCollapsed with new props, toggleContentExpanded and toggleContentCollapsed) that accept ReactNodes as types)? In addition to removing toggleText as a prop

[kmcfaul]

This lgtm.

As far as future API, I'd be in favor of slimming down the props in the next breaking release - we probably could do away with toggleText in favor of toggleContent and deprecate the expanded/collapsed text props.

[thatblindgeye]

Opened a breaking change followup for the API: #12104

[thatblindgeye]

@gitdallas just a merge conflict that needs resolving