[WIP] fixes for manila share encryption

[skook1]

• _get_barbican_client() returns a single object, but the code tries to unpack it as a tuple
• Share type has encryption_support = share_server (string), but backends report it as a list

Change-Id: Id374217b91f7e7dcc2be95fe848e0ef241a2f58b

[kpawar-sap]

check upstream if there are commits w.r.t. this code and backport. we might have not backported all, as some changes added recently upstream