Dismount on Disconnect Gamerule

What the gamerule does:

• If set to true the player will not take the entity they are riding with them when they disconnect from the world
• If set to false, upon disconnecting the entity the player is riding will disappear with them, it reappears with the player upon rejoin

(The default value should be false as thats how it currently works)

Why this is needed:

Players taking thing entity they are riding with them breaks a ton of stuff, for example vehicles. I myself am a datapack developer and whenever I make vehicles I have to include extremely unintuitive and inefficient systems to deal with the player kidnapping the entity they are riding. As without these preventative measures if a player was to ride a vehicle then disconnect it would completely break the vehicle, which allows players to grief.

Also in say for example a public Survival server if a player were to simply jump on another players horse then disconnect and not rejoin the player who owned the horse would essentially have just lost their horse forever

This gamerule, if set to True, fixes all of these issues, as when the player disconnects they would just leave their mount behind rather then them taking it with them