Support for using `disabled` in `toggle-group`

[mimarz]

This came up during actions around #4560.

Quick testing showed we need to update the web, css and react package to support this.

• Suggested using aria-attributes, aria-disabled.

[AnInternetTroll]

Any reason for wanting to support readonly / aria-readonly?
I couldn't find any other libraries that do at least. Most only support disabled on similar components, and setting aria-readonly doesn't look like it's allowed on either input[type=radio] or fieldset

(For some examples of libraries with a toggle-group like component without readonly I looked at DNB, Bootstrap, shadcn, MUI. But of course I could have missed one)

[mimarz]

Any reason for wanting to support readonly / aria-readonly? I couldn't find any other libraries that do at least. Most only support disabled on similar components, and setting aria-readonly doesn't look like it's allowed on either input[type=radio] or fieldset

(For some examples of libraries with a toggle-group like component without readonly I looked at DNB, Bootstrap, shadcn, MUI. But of course I could have missed one)

Your are quick! I was just a bit unclear in writing. We are certain about adding disabled, but support for readonly also came up our brief discussion internally, so decided we have to explore if it makes sense to add readonly or other solutions. This of course has to be looked up against #4584