create UUIDs stdlib package

[JeffBezanson]

closes #25590

[vtjnash]

Looking at the PR, this seems like too much code division. I think we should just keep these couple of functions in Random.

[JeffBezanson]

But nothing else in Random has to do with UUIDs, and nothing in UUIDs has to do with random number generation (it's only a user of it). I don't see why those would need to be grouped together.

[StefanKarpinski]

Also, this is going to end up being a package that implements all five UUID generation methods and therefore depends on SHA and MD5 (which will be, as discussed, moved into stdlib). Presumably one doesn't want Random to gratuitously depend on those packages at that point.

[oxinabox]

Shall a new issue be created: "Add UUID-XYZ functionality to stdlib",
with move SHA.jl and MD5.jl as subtasks?

[StefanKarpinski]

Sure. I would make the tasks "UUID: add uuid3", etc.