Subspace templates: save as template/duplicate from Space settings

[SimoneZaza]

Description

As an admin, I want to create subspace templates As an admin, I want to duplicate subspaces

Acceptance criteria

• [ ] In Space settings > Subspaces, add more button in the list with menu with two options:
• Duplicate
• Save as template
• [ ] Duplicate adds another subspace with the same flow + callouts + context (name Copy of [subspace name])
• [ ] Save as template starts flow from #6800

Additional Context

Screen shots / UX designs / data that are relevant.

Areas that will be affected

To be added during the refinement