Subspace menu: don't show subspaces/events icon when there are none

[SimoneZaza]

Description

As a user, I don't know what to do with these buttons and it makes the whole page to look more complex

Acceptance criteria

• [ ] When there are no subspaces in a subspace, don't show the subspaces icon to anyone (people with the privilege to add events see the option to add subspaces in the space hierarchy block)
• [ ] When there are no events in a subspace, only show the events icon to people with the Create Event privilege
• [ ] Explore UI options (maybe have a call with Simone?)

Additional Context

Screen shots / UX designs / data that are relevant.

Areas that will be affected

To be added during the refinement