t6022: Add test combinations of {content conflict?, D/F conflict remains?}

t6022: Add test combinations of {content conflict?, D/F conflict remains?}

Add testing of the various ways that a renamed file to a path involved in
a directory/file conflict may be involved in.  This includes whether or not
there are conflicts of the contents of the renamed file (if the file was
modified on both sides of history), and whether the directory from the
other side of the merge will disappear as a result of the merge or not.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>