Automatically deactivate old members in the workspace

Automatically deactivate accounts of people who doesn't have the required slack groups.

- [x] Validate if members membership are valid
- [ ] Deactivate members without valid membership
- [ ] Command and/or automation of this process

Start by locating the existing logic that validates whether workspace members have the required Slack groups. Read how member accounts are represented and how administrative commands or automation are organized. Done means members without valid membership are deactivated and the process has a defined command or automation path.

Written by the indexing model from the issue text.