Handle whitespace, add separator to regex in set_directive_lines
    
    We added the separator to the regex in set_directive_lines to avoid
    grabbing just a prefix. This doesn't allow for whitespace around
    the separator.
    
    For the Apache case we expected that the separator would be just
    spaces but it can also use tabs (like Ubuntu 18). Add a special
    case so that passing in a space separator is treated as whitespace
    (tab or space).
    
    https://pagure.io/freeipa/issue/7490
    
    Signed-off-by: Rob Crittenden <rcritten@redhat.com>
    Reviewed-By: Florence Blanc-Renaud <frenaud@redhat.com>