Combobox: issues reported by Axe

[unekinn]

Version number

tested on next (unreleased), probably present in all versions

Description of the bug

After adding stories where the combobox is opened (through interaction testing), and configuring Axe to also consider elements rendered in a portal, we get several rule violations.

In my branch I configure Axe so that these are considered "incomplete" instead of "violation", but we need to look into these before V1.

Steps To Reproduce

Currently reproducible on branch test/setup-chromatic by running Storybook, navigating to the single story (not docs) "Komponenter/Combobox/Preview", and opening the accessibility pane of Storybook.

Additional Information

No response