If the shared files of a distribution are contained in a tarball (see
Dist::Zilla::Plugin::ShareDir::Tarball for why you would want to do that)
automatically extract the archive in a temporary directory and return the path
to that directory.
If called for a regular distribution without a bundle file
(shared-files.tar.gz), it'll return the original shared dir. In other words,
from the consumer point of view, it'll behave just like File::ShareDir.
Submitted by: Geoffroy Desvernay
Approved by: (one of the mentors)