feat(NcAppSidebar): force show navigation for a single tab

[Antreesy]

☑️ Resolves

• Allows to show a tab navigation if there is only one tab available
• Should be non-interactive, act as a visual header

🖼️ Screenshots

🏚️ Before	🏡 After

🚧 Tasks

• Discuss on disabling:
  • keydown events
  • mouse events
  • aria-attributes

🏁 Checklist

• ⛑️ Tests are included or are not applicable
• 📘 Component documentation has been extended, updated or is not applicable
• 3️⃣ Backport to next requested with a Vue 3 upgrade

[ShGKme]

Discuss on disabling:

• keydown events
• mouse events
• aria-attributes

I'd say, it is fine. Yes, it doesn't make much sense to have tab navigation with one tab, but from a11y perspective it is still "active tab one of one"

[susnux]

Makes sense, just one comment about the prop naming but no blocker as I am fine with both if you agree.

[susnux]

/backport to next