Also removes the v2 support from the generic client and restores a
skipped test.

Additionally, the cinderclient.tests.v2.test_availablity_zone module
depends on the v2.shell class, so move that module to v3, update the
v3 AvailablityZone class, and make appropriate adjustments to the
tests and test fixtures.

Change-Id: I7a3cca15f5944141d510a75af6684221c297963b

This adds the import order extension to match what we have in the cinder
repo. This is a linting extension that will check that imports are in
the correct order and the correct grouping so they automatically get
flagged, and it won't be whether reviewers notice and decide to do
anything or not.

Cinder change was Ic13ba238a4a45c6219f4de131cfe0366219d722f for a little
more wordy reasoning.

Also includes updates for noqa tags. Newer version of the linters appear
to want these on the function definition line, not on the decorator
line.

Change-Id: Ibf3f3afbf3bb6ec6613b35f91d4a353c6a391f41
Signed-off-by: Sean McGinnis <sean.mcginnis@gmail.com>

Remove code still adjusting for Python 2
behavior based on version checks.

Change-Id: I29576a824278611d80991dce2501f14f1b262c76

Replace six with Python 3 style code.

Change-Id: I4b97e040f3e790ac114dcd43c68e6b67b1079adf

Using the cinderclient without a subcommand while
passing an optional argument triggers the raw Python
error `ERROR: 'Namespace' object has no attribute
'func'`. This bug can be reproduced by issuing the
command `cinder --os-volume-api-version 3.40`.
Added a default value to `func` and an empty value to
`command` as placeholders so that a help message is
shown instead of the Python error.

Change-Id: Idb51e8635b97f0da2976f3268d5e19100ec77203
Closes-Bug: #1867061

As per victoria cycle testing runtime and community goal[1]
we need to migrate upstream CI/CD to Ubuntu Focal(20.04).

Fixing:
- bug#1886298
Bump the lower constraints for required deps which added python3.8 support
in their later version.
- pep8 error
- Set bionic nodeset for py36 and py37 job.


[1] https://governance.openstack.org/tc/goals/selected/victoria/migrate-ci-cd-jobs-to-ubuntu-fo$

Story: #2007865
Task: #40179

Change-Id: Ibab96807a7747738282732fe0069b9bc197da0ee

pycodestyle does not know about "importutils.try_import"
calls, so we have to either
  a) put them inside a "try" block
or
  b) add "# noqa: E402" to each import after the
     try_import call

Change-Id: Ia545bb689cfdfb57962d74e3957dfb372fd3782b