Re-Implement CollapseExpandAllButtons into site-nav

[itsyme]

Please confirm that you have searched existing issues in the repo

Yes, I have searched the existing issues

Any related issues?

#2299

What is the area that this feature belongs to?

Author Usability

Is your feature request related to a problem? Please describe.

CollapseExpandAllButtons were reverted due to #2299.

Describe the solution you'd like

Integrate the CollapseExpandAllButtons into site-nav as discussed in #2299.

Describe alternatives you've considered

No response

Additional context

No response