Add support for Purity Protection Groups to PureISCSIDriver

Add support for Purity Protection Groups to PureISCSIDriver

We will be needing access to the Protection Group features of Purity to
enable features like Replication and Consistency Groups. To do this we
need to add new helpers for the FlashArray object for the required REST
API methods.

DocImpact: To bring in pgroup support we will need to bump up the
required REST API version to 1.2+ and remove support for 1.0 and 1.1

Implements: blueprint pure-iscsi-add-pgroup-support
Change-Id: Ia446615e0c03b91fc1da75489855e77c29639efa