[MRG] Reorganize traits for easier wasm and native compilation

[luizirber]

• Define a prelude for importing traits used across the codebase
• Update nix configs

Main goal here is to eventually support dependencies that don't compile for wasm (useful for #1221 #848, for example)

[codecov]

Codecov Report

Merging #1836 (9b91409) into latest (92d5f6d) will increase coverage by 0.02%.
The diff coverage is n/a.

❗ Current head 9b91409 differs from pull request most recent head 6fccb48. Consider uploading reports for the commit 6fccb48 to get more accurate results

@@            Coverage Diff             @@
##           latest    #1836      +/-   ##
==========================================
+ Coverage   83.52%   83.55%   +0.02%     
==========================================
  Files         113      113              
  Lines       12187    12183       -4     
  Branches     1630     1630              
==========================================
  Hits        10179    10179              
+ Misses       1750     1746       -4     
  Partials      258      258              

Flag	Coverage Δ
python	90.20% <ø> (ø)
rust	68.27% <ø> (+0.07%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/core/src/cmd.rs	92.98% <ø> (+6.09%)	⬆️
src/core/src/errors.rs	0.00% <ø> (ø)
src/core/src/ffi/hyperloglog.rs	0.00% <ø> (ø)
src/core/src/ffi/nodegraph.rs	0.00% <ø> (ø)
src/core/src/index/linear.rs	17.64% <ø> (ø)
src/core/src/index/mod.rs	61.53% <ø> (ø)
src/core/src/index/sbt/mhbt.rs	64.22% <ø> (ø)
src/core/src/index/sbt/mod.rs	66.76% <ø> (ø)
src/core/src/lib.rs	100.00% <ø> (ø)
src/core/src/signature.rs	65.43% <ø> (ø)
... and 3 more

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