osd/osd_types: introduce last_force_resend_prenautilus

osd/osd_types: introduce last_force_resend_prenautilus

Previously, we renamed the old last_force_resend to
last_force_resend_preluminous and created a new last_force_resend for
luminous+.  This allowed us to force preluminous clients to resend ops
(because they didn't understand the new pg split => new interval rule)
without affecting luminous clients.

Do the same rename again, adding a last_force_resend_prenautilus (luminous
or mimic).

Adjust the OSD code accordingly so it matches the behavior we'll see from
a luminous client.

Signed-off-by: Sage Weil <sage@redhat.com>