Prefer %v over %d,%s and add fmtpercentv custom linter

[gmlewis]

This PR formalizes the preference of %v over the use of %s or %d in this repo by adding a custom linter that enforces this preference.

[codecov]

Codecov Report

❌ Patch coverage is 88.43537% with 17 lines in your changes missing coverage. Please review.
✅ Project coverage is 91.11%. Comparing base (6195c56) to head (69c428e).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
example/commitpr/main.go	0.00%	6 Missing ⚠️
example/actionpermissions/main.go	0.00%	5 Missing ⚠️
example/verifyartifact/main.go	0.00%	3 Missing ⚠️
example/listenvironments/main.go	0.00%	1 Missing ⚠️
example/ratelimit/main.go	0.00%	1 Missing ⚠️
github/repos_contents.go	90.90%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3756   +/-   ##
=======================================
  Coverage   91.11%   91.11%           
=======================================
  Files         187      187           
  Lines       16702    16702           
=======================================
  Hits        15218    15218           
  Misses       1296     1296           
  Partials      188      188           

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[gmlewis]

@stevehipwell - @alexandear - @zyfy29 - might you have time for a code review? Thank you!

[gmlewis]

OK, great idea, @zyfy29! I've renamed urlpercentv to fmtpercentv and generalized it to lint all call expression format strings, not just ones involving assignments. This only flagged 3 perfectly valid lines in the entire repo, so I've gone ahead and added the //nolint comments to those.

PTAL.

[gmlewis]

Thank you, @zyfy29!
Merging.