[New Extension]: pg_uuidv7

### Is there an existing issue for this extension request?

- [x] I have searched for an existing issue, and could not find a duplicate request.

### Extension Name

pg_uuidv7

### Project Repository URL

https://github.com/fboulnois/pg_uuidv7

### Extension Website URL (Optional)

https://github.com/fboulnois/pg_uuidv7

### Short Description

It is kind-of obsolete in PostgreSQL >= 18, but still necessary for upgrades in some setups.

### Main LICENSE Link

https://github.com/fboulnois/pg_uuidv7/blob/main/LICENSE

### License Compliance

- [x] The extension's license (linked above) complies with the list of allowed licenses.

### Known Dependent Extensions

None

### Component Owner and Maintenance Commitment

- [x] I/My organization commit to becoming the Component Owner and maintaining the extension image in the future.

### Additional Notes (Optional)

_No response_

### GitHub Handles of Component Owners

ibotty

### Code of Conduct

- [x] I agree to follow this project's Code of Conduct

Non vengono indicati file di implementazione o test. Inizia esaminando come vengono definite e compilate le estensioni PostgreSQL esistenti in questo repository, quindi confronta il repository pg_uuidv7 e i suoi requisiti di compatibilità con PostgreSQL con questo flusso di lavoro. Il lavoro è completato quando l’immagine dell’estensione viene compilata correttamente e la validazione applicabile del repository ha esito positivo.

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