fix: multicall perfomance

[witem]

It looks like viem has big performance degradation because of calling chunkedCalls.flat() for each item from results in the multicall function. Based on the code I think we can move this flat out of the map cycle, which will significantly improve performance, especially for big multicalls.

Test scenario around 2k balanceOf with batchSize: 30 * 1024:
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PR-Codex overview

This PR focuses on improving multicall performance.

Detailed summary

• Refactored code to remove redundant variable declaration.

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[codecov]

Codecov Report

Merging #1081 (d2d4870) into main (cf4d5d8) will decrease coverage by 12.45%.
The diff coverage is 0.00%.

@@             Coverage Diff             @@
##             main    #1081       +/-   ##
===========================================
- Coverage   99.86%   87.41%   -12.45%     
===========================================
  Files         403      386       -17     
  Lines       31111    30326      -785     
  Branches     2175     1407      -768     
===========================================
- Hits        31068    26510     -4558     
- Misses         38     3788     +3750     
- Partials        5       28       +23     

Files Changed	Coverage Δ
src/actions/public/multicall.ts	37.50% <0.00%> (-62.50%)	⬇️

... and 142 files with indirect coverage changes