decompressZip overloads returning files via a callback

[Fedr]

Adds decompressZip overloads (zip file path and std::istream) that pass every file of the archive to a callback instead of saving it on disk:

using ZipFileCallback = std::function<Expected<void>( const std::string& path, std::vector<char>&& data )>;

• path is relative inside the archive with / separators; folder entries and macOS __MACOSX/ metadata are skipped.
• An error returned by the callback stops decompression and is passed to the caller.
• The entry loop is factored out into forEachZipEntry_, shared with the existing folder-extracting decompressZip; the zip entry is now closed also when reading it fails.
• Fix in the std::istream zip source: ZIP_SOURCE_STAT returned the size from the current stream position to the end instead of the whole stream size. libzip stats the source also when opening an entry, in the middle of the stream, and on macOS failed to open the second entry. The bug was in the existing stream decompressZip too; the new test is the first to cover it.
• "Cannot open zip file" error now includes libzip's error message.
• New test MRMesh.DecompressZipToCallback.

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