Add tests for "Conflicts: module(name)" in MMDResolver.
    
    The test tests installation of multiple streams of single module.
    For example:
     - "app:1" requires "foo:1" and "gtk:1".
     - "foo:1" requires "bar:1".
     - "gtk:1" requires "bar:2".
    "bar:1" and "bar:2" cannot be installed in the same time and therefore
    there need to be conflict defined between them.