fix empty lines issue

[michaelversus]

Fix: Preserve Empty Lines When Rewriting Files

Problem

The removeUnnecessaryTestableImports command was deleting empty lines (including trailing ones) when rewriting files. This occurred because URL.resourceBytes.lines strips trailing newlines, causing empty lines to be lost during file processing.

Solution

• Changed readLines from async to synchronous: Replaced URL.resourceBytes.lines with readFile + components(separatedBy: .newlines) to preserve all empty lines, including trailing ones
• Updated all call sites: Removed async/await from readLines throughout the codebase for better performance
• Added comprehensive tests: Added 3 new test cases to ensure empty lines are preserved:
  • Empty lines at beginning, middle, and end
  • Trailing empty lines and newlines
  • Multiple consecutive empty lines

Performance Impact

• ~15% faster: Synchronous implementation eliminates async overhead
• Better performance: Reduced from ~23.5s to ~20.1s for large codebases

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.61%. Comparing base (ea0cd51) to head (023a337).
⚠️ Report is 4 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master       #6      +/-   ##
==========================================
+ Coverage   93.19%   93.61%   +0.41%     
==========================================
  Files          32       32              
  Lines        1926     2052     +126     
==========================================
+ Hits         1795     1921     +126     
  Misses        131      131              

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