[ENHANCEMENT] Ability to force user registration

[TimothyOutLaw]

Describe the feature you'd like to have implemented
The command /forceregister with which you can force register a player using the specified password.

Is your feature request related to an existing problem? Please describe.
On my server there is a limit of 1 IP address - 1 account. But there are players who play from different computers but on the same IP address, and I want to force the player to register so that he can log into the server.

Additional context
Many plugins have this feature, BUT! In this appeal, adding a team is not important, but fixing the problem that players cannot play from different PCs on the same Internet is important!