ES-511: CHAP auth and Dynamic TargetGroup

[Qeas]

https://jira.tegile.com/browse/ES-511

go lib changes related to this commit - https://github.com/Nexenta/go-nexentastor/releases/tag/v2.7.0

Use cases that were fixed: DynamicTargetLunAllocation is enabled:

• chap auth enabled, but only non chap-auth targets exist. Should not use existing and create a new target with chap auth.
• chap auth enabled, target with chap auth exists. Should use existing if NumOfLunsPerTarget is not exceeded.
• chap auth disabled, only chap-auth targets exist. Should ignore existing target and create and use a new one without chap.
• chap auth disabled, non-chap target exists. Should use existing if NumOfLunsPerTarget is not exceeded.

[EvgeniiIvanov]

sanity - PASS e2e - PASS suggested scenarios - PASS