maint: rewrite spacers check to use new framework

[smartcontracts]

Updates the spacers check to use the new framework for contracts checks written in Go. Adds tests for the functions that this check uses.

[codecov]

Codecov Report

Attention: Patch coverage is 58.33333% with 25 lines in your changes missing coverage. Please review.

Project coverage is 42.76%. Comparing base (ec05937) to head (bb9f8e3).
Report is 11 commits behind head on develop.

Files with missing lines	Patch %	Lines
...s/contracts-bedrock/scripts/checks/spacers/main.go	58.33%	24 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop   #13232      +/-   ##
===========================================
- Coverage    44.21%   42.76%   -1.46%     
===========================================
  Files          807      751      -56     
  Lines        72707    68009    -4698     
===========================================
- Hits         32151    29083    -3068     
+ Misses       37939    36481    -1458     
+ Partials      2617     2445     -172     

Flag	Coverage Δ
cannon-go-tests-32	?
cannon-go-tests-64	?

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...s/contracts-bedrock/scripts/checks/spacers/main.go	66.29% <58.33%> (+66.29%)	⬆️

... and 64 files with indirect coverage changes