feat: Support custom dialog layouts in S2 (#7352)
* Support avatars in S2 ActionButton
* Support nesting menus inside dialog popovers
* Split Dialog into Dialog, StandardDialog, and FullscreenDialog
* lint
* update chromatic stories (more later)
* more chromatic
* ts strict
* Rename StandardDialog back to Dialog, split out Popover, add CustomDialog
* Fix test
* Make ContextualHelpTrigger contain focus
* Close root menu when clicking on an item outside a MenuTrigger
* Reduce props on CloseButton
* Add additional dismiss button on mobile
* Update padding API
