[feat]: Add the equivalent of optgroup to Select and Combobox

[rktyt]

A clear and concise description of what the feature is

Display the options in groups.

Why should this feature be included?

This is a common usage method.

Please provide an example for how this would work

There is a React library called react-select.

The combobox is not yet standardized or implemented natively, but it seems that proposals have been made.
You can find more information in the proposal on Open UI's website.