7904200: Several tests fail to run on Cygwin/Windows

[raneashay]

This patch makes two changes. First, it strips the carriage-return
character from line endings before running grep to check for matches and
second, it broadens the file path regexes to accept both forward and
backward slashes. I validated this patch by running all tests
(bash make/build.sh -- tests) on both Windows and macOS.

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Progress

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Issue

• CODETOOLS-7904200: Several tests fail to run on Cygwin/Windows (Bug - P4)

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• 00: Full (8d57ca97)