Added check for avi SDK version as suggested in review. (#21927)

* Added check for avi SDK version as suggested in review.

* Fixed documentation based on review.

* Renamed module_utils.avi to module_utils.avi_ansible_utils
as import of avi.sdk would fail due to name collisions.

Moved the code to check for AVI version into the ansible modules.

* Updated the module with note about reason for name change.

lib/ansible/module_utils/avi_ansible_utils.py

@@ -27,7 +27,26 @@
 # USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #
 
+# This module initially matched the namespace of network module avi. However,
+# that causes namespace import error when other modules from avi namespaces
+# are imported. In order to avoid the import collisions this was renamed to
+# avi_ansible_utils to allow this module to be ceterpiece of all integration
+# with external avi modules.
+
 import os
+from pkg_resources import parse_version
+
+HAS_AVI = True
+try:
+    import avi.sdk
+    sdk_version = getattr(avi.sdk, '__version__', None)
+    if ((sdk_version is None) or (sdk_version and
+            (parse_version(sdk_version) < parse_version('16.3.5.post1')))):
+        # It allows the __version__ to be '' as that value is used in development builds
+        raise ImportError
+    from avi.sdk.utils.ansible_utils import avi_ansible_api
+except ImportError:
+    HAS_AVI = False
 
 
 def avi_common_argument_spec():