Change loadServiceSpecifiedGroups() so that it can pass along an optional group ID setting value from the `directLinkedGroupId` selector to be an initially focused group.

When loading groups from a service e.g. `loadServiceSpecifiedGroups`, previously it assumed that the `directLinkedGroupId` value would never be used in this context. Since the introduction of the Notebook and specifically in the context of LMS, we have both a service setting which contains the groups  (`settings.services[0].groups <Promise>`) and a top level group to set focus too. (`settings.group`).