test: refactor test suite for excluded paths and extensions

[appleboy]

• Update test function name to TestExcludedPathsAndExtensions
• Add test cases for excluded paths and extensions
• Modify router usage in test function
• Adjust assertions for content encoding, vary, body, and content length

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.35%. Comparing base (d3b1ccd) to head (0ae2960).

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Additional details and impacted files

@@           Coverage Diff           @@
##           master      #80   +/-   ##
=======================================
  Coverage   81.35%   81.35%           
=======================================
  Files           3        3           
  Lines         118      118           
=======================================
  Hits           96       96           
  Misses         19       19           
  Partials        3        3           

Flag	Coverage Δ
go-	81.35% <ø> (ø)
go-1.18	81.35% <ø> (ø)
go-1.19	81.35% <ø> (ø)
go-1.20	81.35% <ø> (ø)
go-1.21	81.35% <ø> (ø)
go-1.22	81.35% <ø> (ø)
macos-latest	81.35% <ø> (ø)
ubuntu-latest	81.35% <ø> (ø)

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