Support --skip-removing-unused-imports in google-java-format-diff.py
Support --skip-removing-unused-imports in google-java-format-diff.py

Fixes #495

COPYBARA_INTEGRATE_REVIEW=https://github.com/google/google-java-format/pull/495 from taesu82:patch-1 91e32d443cf8159a72f05a38146dd9b5d4bf550c
PiperOrigin-RevId: 315560436

sormuras/google-java-format,sormuras/google-java-format,sormuras/google-java-format