Improved symlinks support

[F0xWh1sp3r]

There are archives containing compressed symlinks, and you'd like to be able to unzip them as well. Additionally, some symlinks may point to files in other subfolders within the archive.

Changes proposed in this PR

• Allow extracting archives where symlinks are compressed
• Support symlinks pointing to files in other subfolders within the archive

Tests performed

• Implemented three new tests: testUnzipSymlink, testUnzipCompressedSymlink, testInvalidSymlinkCompressionMethodErrorConditions
• All unit tests pass

[weichsel]

Thanks for providing this PR. Changes look good!

Some things I noticed:

• The FileManager extension doesn't expose the new allowUncontainedSymlinks.
• The allowUncontainedSymlinks parameter is a bit redundant now. Passing a URL pointing to the FS root via symlinksValidWithin has the same effect right? Should we deprecate allowUncontainedSymlinks?
• There's a Swiftlint issue in one of the tests files.

[F0xWh1sp3r]

Thank you for your time and review!

• Added new symlinksValidWithin to the FileManager extension.
• You are right that passing a URL pointing to the FS root via symlinksValidWithin has the same effect. Yes, we should deprecate allowUncontainedSymlinks. With the symlinksValidWithin parameter, we can specify the required boundaries for symlinks. I marked the old functions as deprecated .

[weichsel]

Great - Thanks for the changes!