* add Alert component
* expose Alert
* rename forgotten FLYOUT to POPOVER
* use PopoverRenderPropArg
* organize imports in a consistent way
* ensure Portals behave as expected
Portals can be nested from a React perspective, however in the DOM they
are rendered as siblings, this is mostly fine.
However, when they are rendered inside a Dialog, the Dialog itself is
marked with `role="modal"` which makes all the other content inert. This
means that rendering Menu.Items in a Portal or an Alert in a portal
makes it non-interactable. Alerts are not even announced.
To fix this, we ensure that we make the `root` of the Portal the actual
dialog. This allows you to still interact with it, because an open modal
is the "root" for the assistive technology.
But there is a catch, a Dialog in a Dialog *can* render as a sibling,
because you force the focus into the new Dialog. So we also ensured that
Dialogs are always rendered in the portal root, and not inside another
Dialog.
* add dialog with alert example
* add internal Description component
* add internal Label component
* add RadioGroup component
* expose RadioGroup
* add RadioGroup example
* ensure to include tha RadioGroup.Option own id
* update changelog
* split documentation
Robin Malfait