Add read-only share support for cephfs_native driver
using CephFSVolumeClient's enhanced authorize() interface.
Ensure backwards compatibility with older version of
CephFSVolumeClient by checking it's version attribute, or
lack thereof.
The support for read-only authorize() was added in
CephFSVolumeClient with the following commits in Ceph:
Master branch:
https://github.com/ceph/ceph/commit/011ea5e7fb35ee0
Jewel branch:
https://github.com/ceph/ceph/commit/2cd3ed8a59786be
Change-Id: I29eb45104c04da1706c3978441babe9c4a52ca02
DocImpact
Partially-Implements: bp cephfs-native-driver-enhancements