fix(groups): displays correct group content access options for each content access mode

Content access options for public groups:
 - Private
 - Logged in users
 - Public
 - Members of the group

Content access options for groups using members-only policy:
 - Private
 - Members of the group

Refs #6142
Merge pull request #6393 from juho-jaakkola/group_access_settings

Display correct access options for group content