gh-89083: add support for UUID version 6 (RFC 9562) (#120650)

Add support for generating UUIDv6 objects according to RFC 9562, §5.6 [1].

The functionality is provided by the `uuid.uuid6()` function which takes as inputs an optional 48-bit
hardware address and an optional 14-bit clock sequence. The UUIDv6 temporal fields are ordered
differently than those of UUIDv1, thereby providing improved database locality.

[1]: https://www.rfc-editor.org/rfc/rfc9562.html#section-5.6

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Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>
Co-authored-by: Victor Stinner <vstinner@python.org>