Allow `COA.withdraw` call to run when there is a possible rounding error

[m-Peter]

Closes https://github.com/onflow/flow-go/issues/6856

In this case, we perform the withdrawal, by simply truncating the remainder that cannot fit in a Flow token vault. When the attoFlow balance is too small to fit in a Flow vault, we panic with a dedicated error message.

[m-Peter]

cc @sisyphusSmiling Can you take a look at this approach, and the added test cases?

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 76.47059% with 4 lines in your changes missing coverage. Please review.

Project coverage is 40.27%. Comparing base (6e6c6cd) to head (4669999).

Files with missing lines	Patch %	Lines
fvm/evm/types/balance.go	0.00%	2 Missing :warning:
utils/unittest/execution_state.go	0.00%	2 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6877      +/-   ##
==========================================
- Coverage   41.31%   40.27%   -1.05%     
==========================================
  Files        2164     2020     -144     
  Lines      189596   180524    -9072     
==========================================
- Hits        78337    72701    -5636     
+ Misses     104735   101793    -2942     
+ Partials     6524     6030     -494     

Flag	Coverage Δ
unittests	40.27% <76.47%> (-1.05%)	:arrow_down:

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[sisyphusSmiling]

Thanks for the changes @m-Peter! The test cases and behavior look good to me, just left one question.