Remove chunk data serialization workaround in feather-anvil

[Schuwi]

Because serde derived serialization of the NBT Byte/Int/LongArray type was previously impossible via hematite_nbt, a workaround was in place, implementing serialization manually via the non-serde hematite_nbt API.
Now that serde serialization support is implemented via PistonDevelopers/hematite_nbt#52 this PR seeks to remove the manual serialization and use serde derive macros in feather-anvil instead. This removes a lot of verbose code and makes improving the data model way faster and less error-prone.

I tested loading, flying around in and saving of a vanilla world. No errors occured and everything seemed to be fine though I haven't inspected the NBT files. All tests complete successfully.

This ties in with my work on world loading problems in #269.

[Schuwi]

Weeeell, today I've learnt to be nice to clippy, and run it with --all-targets. It... tends to help 😅

[caelunshun]

Thank you, and I'm sorry about the delay! Great work on getting rid of that NBT workaround.