CA-141002: Enable ALUA auto-detection for DGC arrays

We have seen quite a few incidents where a configuration mismatch (ALUA vs.
DGC) between XS and the array caused confusion and got escalated: SCTX-1780,
SCTX-1333, CA-112771, CA-124429. This updated configuration will prevent such
misconfiguration incidents from reocurring, as XS will dynamically adapt to the
configuration on the array.

The partner has completed the qualification of the updated multipath
configuration with their storage arrays.

Signed-off-by: Robert Breker <robert.breker@citrix.com>
Acked-by: Germano Percossi <germano.percossi@citrix.com>

(cherry picked from commit f93497ba)
Signed-off-by: Germano Percossi <germano.percossi@citrix.com>

GitHub: closes #215 on xapi-project/sm
CA-142451: Failed to report all LUNs advertised on targets sharing the same IQN

If a multicontroller array advertises its targets using the same IQN
but different IPs and the LUNs in those targets are distinct,
we are able to show only LUNs coming from the first IP address.

The fix reinstates a line that was removed in commit 391bdf055dff
in our old sm.hg repository.
The purporse of the line is to first check that we have
a valid active iscsi connection using the original pair IP,IQN.
Only if it fails (it should not in my opinion) we fall back to
other ip addresses.

Signed-off-by: Germano Percossi <germano.percossi@citrix.com>
Reviewed-by: Chandrika Srinivasan <chandrika.srinivasan@citrix.com>
Imported-by: Mate Lakat <mate.lakat@citrix.com>

(cherry picked from commit 66c89ea for [CA-142451])

GitHub: closes #217 on xapi-project/sm
CA-142451: Unit tests

Covering changes related to CA-142451.

Signed-off-by: Flavien Quesnel <flavien.quesnel@citrix.com>
Reviewed-by: Mate Lakat <mate.lakat@citrix.com>