Sort dependencies in Cargo.toml files

[samestep]

Currently most of the [dependencies] lists in Cargo.toml files are close to sorted but not quite, making it a bit confusing to figure out where to insert a new dependency. This PR sorts them all.

[pchickey]

I wonder if we should leave a comment at the top of these lists indicating they are sorted and to please respect the sort order on changes? On the other hand that seems noisy. I wish this was something cargo fmt did automatically.

[samestep]

@pchickey I'm not sure; I was going to say it might not be too hard to add a Python script using tomllib to check in CI that all the dependencies are sorted, but then I remembered that the following cases wouldn't be completely trivial:

• different groups of dependencies separated by comments
• individual dependencies specified in separate TOML tables

Still possible, though.

[pchickey]

Yeah, I don't think we should invent nonstandard tooling here. Best effort is good enough. Most people will notice a well-sorted list and maintain it, and if they don't, not the end of the world.