MDL-70631 files: Fix performance of zip_packer::extract_to_pathname()
The original implementation was based on ZipArchive::getStream() which
turns out to be very slow and if the archive contains many files, the
unzipping performance is very slow.
The patch changes the implementation to use ZipArchive::extractTo()
unless the extracted entry path contains a folder name ending with dot
(such as some/path./to/file.txt). There is a known upstream bug in the
PHP ZIP extension #77214 (also #74619 and #69477) so that we fall back
to keep using the stream in those cases.