t6022: Add tests with both rename source & dest involved in D/F conflicts

t6022: Add tests with both rename source & dest involved in D/F conflicts

Having the source of a rename be involved in a directory/file conflict does
not currently pose any difficulties to the current merge-recursive
algorithm (in contrast to destinations of renames and D/F conflicts).
However, combining the two seemed like good testcases to include for
completeness.

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