Move clients::mutex to sync module

[SabrinaJewson]

Description

Rename clients::mutex to sync and add doc comments to it.

Motivation and Context

clients::mutex shouldn’t really be inside clients IMO because it has nothing inherently to do with the differerent clients. I was considering removing the module entirely, but I think it’s nice to keep it contained. sync is a better name than mutex since it’s more general.

Dependencies

None.

Type of change

• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How has this been tested?

• Test A: cargo test --no-default-features --features client-reqwest,reqwest-default-tls,env-file
• Test B: cargo test --no-default-features --features client-ureq,ureq-rustls-tls,env-file

Is this change properly documented?

I will add a changelog entry.

[marioortizmanero]

Thanks a lot for the contributions!

Looks good to me! The only nitpick I have is that maybe sync::sync should be renamed to sync::blocking? It seems less confusing. It's even pointed out by clippy (haha, I like that the lint is called module-inception).

[SabrinaJewson]

Good point, I’ve done that. I do run Clippy locally but it didn’t complain about it for some reason…how strange.

[marioortizmanero]

Yeah, since it's a workspace you have to use cargo clippy --all or something like that. I think. I'll merge after you do a cargo fmt, it seems like the imports aren't sorted anymore :P

Edit: oh, and there are conflicts now