Accept ReactNode for group in MultiSelect

[Psvensso]

Hi,
the ComboboxGroupProps.label is a ReactNode but the ComboboxItemGroup.group and OptionsGroup.group is actually a string on the interface so from the outside you can only provide it with a string.

I wanted to render my own markup here and by casting the group option type (just ugly 'any' cast) the actuall render works just fine. Is there any particular reason why this is a string or could we allow it to be a ReactNode so we can render it ourself?

I dont see any other usage of the group where it needs to be a string either (like a key for example).

[rtivital]

Added in 9.4 release, will be available at the end of June