Updates volume for 2.0.0

Changes sdk calls to use the proxy layer where convenient.

Ensures resources are converted to dict before returns.

Changes the name of various parameters to match sdk attributes. Adds the
old attribute names as aliases to maintain backward compatibility.

Adds detailed return documentation.

Removed the ability to create volumes in specific projects. Users
looking to do that can use the auth parameter to specify what project
is relevant

Removes conditionals in tests that maintained support for ancient
openstack and sdk releases.

Depends-On: https://review.opendev.org/c/openstack/openstacksdk/+/854293
Change-Id: I3c4f4209f2ca6348370a45473bdb0d111b2439b6