What do you think about allowing a Card to expand when an element is clicked (such as CardHeader) instead of having a button?

Related, it would be nice if there was an option of allowing the developer to control the expanded state of an element through props in case they wanted to do something custom.

Its not exactly the same but PanelGroups in React-Bootstrap have a nice API that could provide some inspiration.

I can work on a PR if there is interest but wanted to check first.