Add Fibre Channel drivers for Huawei storage systems

This is the third patch, changes as follows:
1.Add Fibre Channel drivers for huawei OceanStor T series and Dorado
series arrays. Dorado FC driver inherits codes from FC driver of T.
The FC drivers call module ssh_common which has been defined in
the preview patch: https://review.openstack.org/#/c/41721/
2.Add unit test for the changes.

Implements: blueprint huawei-fibre-channel-volume-driver
Change-Id: Iee20d9746004b57777a7161827b4a23cb10f0859
Merge "Add Fibre Channel drivers for Huawei storage systems"