DrawableOsuMenuItem
It didn't ever really make sense for it to be sharing the implementation details of that (e.g. colouring of primary/dangerous actions), and with the hotkey display things got outright hacky, so I'm decoupling it entirely.
HasSubmenu
Property has been removed in the appropriate framework-side PR and instead folded into `IsActionable`. See: https://github.com/ppy/osu-framework/pull/5658#discussion_r1114834647