include/ceph_features: add NVMEOFHA feature bit

include/ceph_features: add NVMEOFHA feature bit

Normally, we'd just use the SERVER_SQUID or SERVER_T flags instead of
using an extra feature bit.  However, the nvmeof ha monitor paxos
service has had a more complex development journey.  There are users
interested in using the nvmeof ha feature in squid, but it didn't make
the cutoff for backporting it.  There's an upstream nvmeof-squid branch
in the ceph.git repository with the patches backported for anyone
interested in building it.

However, that means that users of our normal stable releases will see
the feature added to the monitor one release after anyone who chooses to
use the nvmeof-squid branch.  We could disallow upgrades from
nvmeof-squid to T, but by adding a feature bit here we make such a
restriction unnecessary.

Signed-off-by: Samuel Just <sjust@redhat.com>