Leverage rand_core::RngCore implementations in Rng

[appcypher]

Summary

Leverage RngCore in Rng implementation

This PR turns Rng random_bytes method into a default method that depends on RngCore implementation. It allows us directly use existing RngCore implementations out there without wrapping them, like proptest TestRng.

Test plan (required)

• Testing the Rust core.

  cargo test -p wnfs --release

• Testing the wasm bindings.

  cd crates/wasm

  yarn playwright test

Closing issues

Fixes #55

[codecov-commenter]

Codecov Report

Merging #60 (bb15880) into main (a38daf5) will decrease coverage by 0.24%.
The diff coverage is 95.65%.

@@            Coverage Diff             @@
##             main      #60      +/-   ##
==========================================
- Coverage   80.09%   79.84%   -0.25%     
==========================================
  Files          28       28              
  Lines        2215     2213       -2     
==========================================
- Hits         1774     1767       -7     
- Misses        441      446       +5     

Impacted Files	Coverage Δ
crates/fs/common/utils.rs	78.57% <ø> (-0.60%)	⬇️
crates/fs/private/rng.rs	75.00% <75.00%> (ø)
crates/fs/private/directory.rs	85.96% <100.00%> (ø)
crates/fs/private/forest.rs	82.69% <100.00%> (ø)
crates/fs/private/key.rs	76.00% <100.00%> (ø)
crates/fs/private/namefilter/bloomfilter.rs	85.71% <100.00%> (-0.23%)	⬇️
crates/fs/private/node.rs	72.64% <100.00%> (ø)
crates/fs/common/blockstore.rs	79.31% <0.00%> (-2.84%)	⬇️
crates/fs/private/hamt/node.rs	90.81% <0.00%> (-1.44%)	⬇️

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[matheus23]

Clean!
🚀

(I really want to pick a gif, but I'm on a restricted network rn :D)