Don't use `util.get_repo_urls()` to resolve provided repositories, but
implement osbuild-specific variant of the function named
`_get_repo_urls(). The reason is that the function from `utils`
transforms repositories defined as dicts to strings, which is
undesired for osbuild. The requirement for osbuild is to preserve the
dict as is, just to resolve the string in `baseurl` to the actual
repository URL.
Add a unit test covering the newly added function. It is inspired by a
similar test from `test_util.py`.
Signed-off-by: Tomáš Hozza <thozza@redhat.com>
e3072c3d5f