Add wheel support to InstallRequirement.get_dist()
Add wheel support to InstallRequirement.get_dist()

Before it did support only requirements that had their
metadata prepared to a local directory.
WIth wheels that does not happen so we need to
handle that case too.

get_dist() is used by the metadata property of InstallRequirement,
which in turn is useful to obtain metadata
of the RequirementSet returned by the resolver.

pradyunsg/pip,pfmoore/pip,sbidoul/pip,pypa/pip,pradyunsg/pip,sbidoul/pip,pfmoore/pip,pypa/pip