cmake: pass unparsed args to add_ceph_test()

cmake: pass unparsed args to add_ceph_test()

this allows us to pass extra argument to the script or executable to
further customize its behavior when testing.

also fix all the callers of add_ceph_unittest(), as there is no need to
repeat the executable, which is also used as the name of the test.

Signed-off-by: Kefu Chai <kchai@redhat.com>