Currently, various tools fail to remove the read-only directory, which
is created as an output from the test suite. This for example breaks
package building when tests are enabled. Let's make it writable again
when test is done to fix the issue.

Fixes: https://gitlab.gnome.org/GNOME/gnome-autoar/-/issues/34

An extraction of raw format archives leads to crashes currently.
This is because the generic "data" string is returned from libarchive
instead of the real pathname, which is not expected currently. Let's
handle this case properly and fallback to the source basename.

Fixes: https://gitlab.gnome.org/GNOME/gnome-autoar/-/issues/38

An extraction to the root of an archive which contains the "/" path
leads to crashes. Let's handle this rare corner case.

Relates: https://gitlab.gnome.org/GNOME/gnome-autoar/-/issues/38

The raw format archives are not tested currently. Let's two test cass
to reduce change that their support will be broken again.

Relates: https://gitlab.gnome.org/GNOME/gnome-autoar/-/issues/38

When building Fedora package, I see many "may be used uninitialzed"
warnings. I am not sure why but I don't see those warnings locally even
when `-Wmaybe-uninitialized` is used. Anyway, this is because the
`g_autofree` and `g_autoptr` variables are not explicitely initialized
as mentioned in the documentation. Let's initialize them to get rid of
those warnings.