The original menu implementation allowed for a childEl to be passed

in, containing a custom element to render in the menu item. This item

took precedence over the "inner" part of the menu item, but this meant

that the implementation just had to duplicate that or risk breaking both

styling and events.
This is now applied inside the "label" area instead. That fixes styling

issues, allows for icons and shortcuts alongside a custom element, and

gives the implementation free reign to put whatever they want in an item

without breaking things.
While fixing this, I found that custom child elements couldn't be

provided during crafting. This is now accepted as a valid option on the

subcomponent.

Unit tests pass.