t6022: Add tests for rename/rename combined with D/F conflicts

t6022: Add tests for rename/rename combined with D/F conflicts

Add tests where one file is renamed to two different paths in different
sides of history, and where each of the new files matches the name of a
directory from the opposite side of history.  Include tests for both the
case where the merge results in those directories not being cleanly
removed, and where those directories are cleanly removed during the merge.

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