maint: update unused imports check to use new pattern

[smartcontracts]

Updates the unused imports contract check to use the new framework that we recently merged.

[codecov]

Codecov Report

Attention: Patch coverage is 29.16667% with 17 lines in your changes missing coverage. Please review.

Project coverage is 42.73%. Comparing base (c3e535c) to head (928c06a).
Report is 3 commits behind head on develop.

Files with missing lines	Patch %	Lines
...acts-bedrock/scripts/checks/unused-imports/main.go	29.16%	17 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop   #13227      +/-   ##
===========================================
- Coverage    44.35%   42.73%   -1.63%     
===========================================
  Files          807      751      -56     
  Lines        72707    67999    -4708     
===========================================
- Hits         32247    29056    -3191     
+ Misses       37831    36501    -1330     
+ Partials      2629     2442     -187     

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
...acts-bedrock/scripts/checks/unused-imports/main.go	42.59% <29.16%> (+42.59%)	⬆️

... and 65 files with indirect coverage changes

[blmalone]

LGTM