RequireFilesExist should accept a file reached through .. (#977)

[AzazelSensei]

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RequireFilesExist compared the configured path's URI to getCanonicalFile(). A path with .. never matches, so a file that exists is reported missing. I hit this on macOS with ${project.basedir}/../../../README.adoc.

I collapse .. first and then compare the file names. That keeps the Windows case check and also survives /var vs /private/var on macOS temp dirs.

TestRequireFilesExist.testFileExistsThroughDotDot fails on the old URI compare.

Fixes #977