Normalize specifiers by sorting

[konstin]

We currently normalize package and extra names and drop the whitespace from version specifiers, but we were not normalizing the order of the specifiers. By sorting them we match the behavior of packaging and become independent of build backends reordering specifiers (#6332).

Surprisingly, the snapshot diff isn't large - most people were already writing sorted specifiers. Still, this will lead to observable differences in lockfiles between releases in cases where there are entries in requires-dist that were not previously sorted (while the total number of requires-dist is already small compared to the overall lockfile).

[BurntSushi]

This makes sense to me, but as discussed offline, we need to decide how we want to handle changes like this where it could cause a change to the lock file contents. The most annoying manifestation likely occurs when multiple people working on the same project use different versions of uv to make a change to the lock file. This could result in ping-ponging. Although it's worth saying that this change doesn't impact how lock files are read, so there is a high degree of compatibility.

I'm inclined to merge this as a bug fix, but I think there is a big known unknown here: we have no systematic way at present of measuring the impact of a change like this. For example, if most specifiers are sorted in lock files already, then this has very limited impact and seems okay to merge. On the other hand, if this changed almost every lock file, then that kind of impact would probably demand us to manage it differently.

My sense though, based on the snapshot updates here, is that the impact is much closer to the limited end of the spectrum.

[konstin]

I've confirmed that uv lock doesn't change requires-dist when there aren't other changes anyway (the noop behavior remains untouched), i.e. there will only be changes to the lockfile (and could ping-pong between versions) when it gets changed anyway, and even then i expect those cases to be rare, so i'm merging this for the next release.