feat: Allow non-tab elements in the tabs component tablist

[RehanSaeed]

🙋 Feature Request

I have the requirement to add headings to groups of tabs e.g. like so. I want to be able to add content to the tab slot which is not a fluent-tab. In my case I'd like to add a h2 tag.

🤔 Expected Behavior

Any non-fluent-tab content should not be treated like a tab.

😯 Current Behavior

My h2 tags are treated like they are tabs and things like aria-selected etc. are added to it:

💁 Possible Solution

I cannot use the start and end slots because I also want to add headings in between tabs.

Only look for fluent-tab components to apply customize. I currently set aria-disabled="true" on my h2 tag to work around this issue, as this causes the element to be ignored by the fluent-tabs component.

[chrisdholt]

Thanks for the issue - I'm hesitant to support this feature specifically because the tabs slot in as a direct child of a tablist which only specifies elements with a role of tab as allowed children: https://w3c.github.io/aria/#tablist. If an element with a different role were to be slotted I would expect a violation to occur.

[chrisdholt]

Closing per the above.