Improve pypechain import

[sentilesdal]

Allows for this import style and usage:

from pypechain import pypechain

abi_dir = "./abis"
out_dir = "./types"
line_length = 80
pypechain(abi_dir, out_dir, line_length)

[codecov-commenter]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (b5ff593) 76.49% compared to head (1317b2b) 83.08%.

Files	Patch %	Lines
pypechain/main.py	33.33%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #94      +/-   ##
==========================================
+ Coverage   76.49%   83.08%   +6.59%     
==========================================
  Files          40       40              
  Lines        1770     1774       +4     
==========================================
+ Hits         1354     1474     +120     
+ Misses        416      300     -116     

Flag	Coverage Δ
unittests	83.08% <66.66%> (+6.59%)	⬆️

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