This ticket includes the creation of a "user activate" subcommand in mmctl based on the Mattermost CLI command that can be found in cmd/mattermost/commands/user.go.
To achieve this, the command can use the Update User Active status endpoint, and it should mimic the structure, arguments and behavior of the Mattermost CLI command.
With mmctl connected to a server:
1. Use the "mmctl user deactivate" command to deactivate a user
2. Check in the system console the status of the user
3. Use the "mmctl user activate" to activate a user
4. Check in the system console the status of the user
Expected: in steps 2 and 4, the user should have been correctly deactivated and activated respectively