[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