Implement setting groups for worker

Implement setting groups for worker

One of the assumptions of Boruta system is that every user will have
access to the limited amount of resources. It is done by groups.
Initially Worker is not assigned to any. In order to add or remove
group from the list a new list should be created and SetGroups used
to replace it.

Change-Id: Id17eb5feab091dbaa90404d8a09bf4e52537fc61
Signed-off-by: Aleksander Mistewicz <a.mistewicz@samsung.com>
Reviewed-on: https://mcdsrvbld02.digital.local/review/49060
Reviewed-by: Maciej Wereski <m.wereski@partner.samsung.com>
Tested-by: Maciej Wereski <m.wereski@partner.samsung.com>