ref(client): Debug, Eq, Hash, PartialEq for ImageLayer; convert annotations to BTreeMap

[vdice]

• Update ImageLayer to derive Debug, Eq, Hash and PartialEq traits
• Breaking: Convert annotations from a HashMap to a BTreeMap per https://github.com/krustlet/oci-distribution/pull/121#discussion_r1544777159, so that we don't need a custom Hash impl for ImageLayer

Changeset motivated by the need to differentiate and deduplicate collections of ImageLayers.

[thomastaylor312]

@vdice heads up that it looks like the BTreeMap import didn't get picked up in the windows build for some reason

[vdice]

@thomastaylor312 thanks - looks like I didn't update the import in examples/wasm/push.rs. Now updated; hopefully that was the issue.

edit: nope; still failing... looking

edit 2: okay, needed to update examples/wasm/main.rs as well. Weird - nothing complained when I ran my usual just build && just test flow... but once I started running the cargo test command from the justfile-windows file, I was able to repro. Turns out the warnings also occur on main, but at least there should be no error now.

[thomastaylor312]

Thanks for soldering through that @vdice. Just waiting on a second opinion from @flavio on the breaking aspect of this

[flavio]

Sorry, I was on vacation. This change looks good to me

[vdice]

Thanks so much @thomastaylor312 and @flavio!