`CREATE DATABASE` location

#451 implemented support for `CREATE DATABASE` queries.
It includes two tests for the query.

`Statement::CreateDatabase` has two additional fields: `location` and `managed_location`. The syntax for these is not detailed; neither in the PR, nor anywhere else I can find.

1. Perhaps this could be detailed in the docs
2. Perhaps tests could be added for these fields
3. What is the syntax for these fields?

Inizia esaminando la PR #451 e i due test esistenti per CREATE DATABASE, quindi ispeziona Statement::CreateDatabase, inclusi i campi location e managed_location. Stabilisci la sintassi per entrambi i campi e documentala aggiungendo test che coprano la sintassi, in modo che il comportamento sia chiaro.

Scritto dal modello di indicizzazione a partire dal testo della issue.