Replace hard-coded kdcproxy path with WSGI script
    
    mod_wsgi has no way to import a WSGI module by dotted module name. A new
    kdcproxy.wsgi script is used to import kdcproxy from whatever Python
    version mod_wsgi is compiled against. This will simplify moving FreeIPA
    to Python 3 and solves an import problem on Debian.
    
    Resolves: https://pagure.io/freeipa/issue/6834
    
    Signed-off-by: Christian Heimes <cheimes@redhat.com>
    Reviewed-By: Martin Basti <mbasti@redhat.com>