`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?

Comienza revisando el PR #451 y las dos pruebas existentes de CREATE DATABASE; después, inspecciona Statement::CreateDatabase, incluidos sus campos location y managed_location. Establece la sintaxis de ambos campos y documéntala añadiendo pruebas que cubran la sintaxis, para que el comportamiento sea claro.

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