Fix input parameter names and types.

[sentilesdal]

There were a few issues with structs being used as input parameters showing as 'tuple' instead of the struct type. The names were also not coming through as the default 'arg' names if they were blank. both issues fixed now.

• cleanup names, multimethod attribute in template
• add more example abis
• update snapshots

[codecov-commenter]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (aab5a29) 66.79% compared to head (ac8c0a1) 66.85%.

Files	Patch %	Lines
pypechain/utilities/abi.py	87.50%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #39      +/-   ##
==========================================
+ Coverage   66.79%   66.85%   +0.06%     
==========================================
  Files          17       17              
  Lines         527      528       +1     
==========================================
+ Hits          352      353       +1     
  Misses        175      175              

Flag	Coverage Δ
unittests	66.85% <87.50%> (+0.06%)	⬆️

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