Add SelectFileystem implementing ceph_select_filesystem which can be
used to select a cephfs by name, prior to calling mount, when the ceph
cluster hosts more than one cephfs file system.
Fixes: #262Fixes: #818
Original-Version-By: "Arvid E. Picciani" <arvid@kraud.cloud>
Original-PR-URL: https://github.com/ceph/go-ceph/pull/819
Signed-off-by: John Mulligan <jmulligan@redhat.com>