Remove all cinderclient.v2 classes, mostly incorporating them into
their v3 counterparts and updating the tests and test fixtures.

Depends-on: https://review.opendev.org/c/openstack/horizon/+/800814

Change-Id: I335db5c1799edb2273bf8bfc9e1bc9de404a4ba5

Cinder and cinderclient assumes an attachment create request will
always contain instance_uuid. This is not true when glance calls
cinder for attachment in glance cinder configuration.
This patch (along with the cinder patch) make the instance_uuid
optional and allow glance to do attachments without passing
instance_uuid.

Change-Id: Ifbaca4aa87d890bc5130069638d42665b914b378

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

In python 3, all strings are considered as unicode string.

This patch drops the explicit unicode literal (u'...')
or (u"..") appearances from the unicode strings.

Change-Id: I9902966892a1dc4f85d449dfe580fb128647487b

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>