config.yml - create users and groups separately, allow users to have supplementary groups

### Description

Hello, currently it is not possible for a user to be in several groups, so a share access could be managed by groups only (e.g. group per share). It could be solved by dividing user and groups definitions in confing.yml and allowing users to have multiple groups in group attribute (or use group for a main group and some other attribute for supplementary group list).