feat: optimize dynarray and bytearray copies

[charles-cooper]

What I did

include the length word in the batch copy instead of issuing a separate store instruction.

brings CurveStableSwapMetaNG.vy down by 315 bytes (~1.5%) and VaultV3.vy by 45 bytes (0.25%) in both --optimize codesize and --optimize gas modes.

How I did it

How to verify it

Commit message

include the length word in the batch copy instead of issuing a separate
store instruction.

brings CurveStableSwapMetaNG.vy down by 315 bytes (~1.5%) and VaultV3.vy
by 45 bytes (0.25%) in both `--optimize codesize` and `--optimize gas`
modes.

Description for the changelog

Cute Animal Picture

[codecov-commenter]

Codecov Report

Merging #3499 (727be2a) into master (5dc3ac7) will decrease coverage by 0.04%.
The diff coverage is 100.00%.

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@@            Coverage Diff             @@
##           master    #3499      +/-   ##
==========================================
- Coverage   89.19%   89.16%   -0.04%     
==========================================
  Files          84       84              
  Lines       10948    10953       +5     
  Branches     2503     2503              
==========================================
+ Hits         9765     9766       +1     
- Misses        771      775       +4     
  Partials      412      412              

Impacted Files	Coverage Δ
vyper/codegen/core.py	87.19% <100.00%> (-0.23%)	⬇️

... and 1 file with indirect coverage changes

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