Unify workflow napari container with ordered steps

[alessandrofelder]

It would be nice to have a re-useable container widget for workflows that have steps in a napari plugin. We would expect these steps to be executed in order from top to bottom of a napari plugin.

See maybe https://stackoverflow.com/questions/11077793/is-there-a-standard-component-for-collapsible-panel-in-qt for inspiration for a possible implementation

[alessandrofelder]

Alternative to consider, suggested by @lauraporta, would be next/back buttons.