cephfs_native: add read-only share support

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
diff --git a/manila_tempest_tests/tests/api/test_rules_negative.py b/manila_tempest_tests/tests/api/test_rules_negative.py
index 376ba85..48e2891 100644
--- a/manila_tempest_tests/tests/api/test_rules_negative.py
+++ b/manila_tempest_tests/tests/api/test_rules_negative.py
@@ -19,7 +19,6 @@
 from tempest import test
 import testtools
 
-from manila_tempest_tests import share_exceptions
 from manila_tempest_tests.tests.api import base
 from manila_tempest_tests import utils
 
@@ -348,16 +347,6 @@
                           self.share["id"], self.access_type, self.access_to,
                           access_level="su")
 
-    @test.attr(type=[base.TAG_NEGATIVE, base.TAG_API_WITH_BACKEND])
-    def test_create_access_rule_cephx_with_unsupported_access_level_ro(self):
-        rule = self.shares_v2_client.create_access_rule(
-            self.share["id"], self.access_type, self.access_to,
-            access_level="ro")
-        self.assertRaises(
-            share_exceptions.AccessRuleBuildErrorException,
-            self.shares_client.wait_for_access_rule_status,
-            self.share['id'], rule['id'], "active")
-
 
 def skip_if_cephx_access_type_not_supported_by_client(self, client):
     if client == 'shares_client':