doc:it_IT: first translation for locking/

To begin with:
- locking/index.rst
- locking/lockdep-design.rst
- locking/lockstat.rst
- locking/lockturture.rst
- locking/locktypes.rst

And RCU/torture.rst to avoid broken references.

Signed-off-by: Federico Vaga <federico.vaga@vaga.pv.it>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20240106233820.30454-1-federico.vaga@vaga.pv.it