Menu items should be able to collapse and expand

## Background
The current implementation presents the entire page and folder structure without any limits.
I agree with the warning not to create folder hierarchies deeper than 2, but we must present hundreds of features.
- We can split them into separate topics (folders), but there is still a problem with usability.

## New feature proposal
- The feature to collapse all or selected menu nodes with sub-nodes would be helpful here.