fix: Decompression write through symlink

[valoq]

If a symbolic link already sits in the folder you unpack into and it has the same name as something the archive unpacks, ouch follows that link. The files are written where the link points instead, and anything already there is overwritten.

This is another case of writing outside the specified directories.
The Landlock sandbox blocks this on Linux, but on On macOS, on Windows it could potentially be exploited.
The only way I see to exploit this, would be to trick a user to extract an archive twice.

This also fixes a few additional issues found along the way.

• the dialog for the file conflict during extraction showed the compression prompt instead of decompression, missing the merge option.
• rar archives did not count extracted folders in the number of unpacked files
• tar symlink and hard link entries failed with "file exists" instead of showing the conflict dialog