[codec] Add Zeroed type

[fedemagnani]

Introduced the Zeroed codec type: a useful type for encoding/decoding zero-padded data of a specific length without any memory allocation.

When reading from buffer, it avoids heap-allocating a vector by "peeking" the input buffer via .chunk()[..len]: the buffer is advanced only if the given chunk has all zeros

Closes #1703

[BrendanChou]

Would it make more sense to have Zeroed<const N: usize> similar to the FixedSize type in utils/? Then the read_cfg Read::Cfgtype could be()`

[fedemagnani]

Unfortunately it looks like that in stable Rust currently, only constants that are independent of generic type resolution can be used in const generics.

Associated constants of traits (e.g. V::SIZE) are type-dependent and therefore cannot currently appear in const generic arguments. This is the tracking issue on rust to enable generic const expres

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.29%. Comparing base (b8610fc) to head (b61820e).
⚠️ Report is 16 commits behind head on main.

@@            Coverage Diff             @@
##             main    #1804      +/-   ##
==========================================
+ Coverage   92.18%   92.29%   +0.11%     
==========================================
  Files         302      305       +3     
  Lines       77980    79221    +1241     
==========================================
+ Hits        71885    73118    +1233     
- Misses       6095     6103       +8     

Files with missing lines	Coverage Δ
codec/src/types/zeroed.rs	100.00% <100.00%> (ø)
storage/src/store/operation.rs	81.78% <100.00%> (+0.59%)	⬆️

... and 52 files with indirect coverage changes

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