Add UUID v6 and/or v8?

[PallHaraldsson]

UUIDv7 is being added to PostgreSQL, so I think it might be important, and the ones added to Python (which most important? Also add this trivial NIL and MAX?);

https://docs.python.org/3.14/whatsnew/3.14.html#uuid

• Add support for UUID versions 6, 7, and 8 via uuid.uuid6(), uuid.uuid7(), and uuid.uuid8() respectively, as specified in RFC 9562. (Contributed by Bénédikt Tran in gh-89083.)
• uuid.NIL and uuid.MAX are now available to represent the Nil and Max UUID formats as defined by RFC 9562. (Contributed by Nick Pope in gh-128427.)
• Allow to generate multiple UUIDs at once via python -m uuid --count. (Contributed by Simon Legner in gh-131236.)

EDIT: we have UUID, uuid1, uuid4, uuid5, uuid7, uuid_version; v7 recently added (I don't find it in docs), so I change title.

[StefanKarpinski]

UUIDv8 seems to be reserved for vendor experimentation? The other things seem good if you want to have a crack at adding them. The trickiest part would be the counter bits. My suggestion would be using global atomics to ensure correct concurrent counter usage.

[tp2750]

Related #25841