feat!: use session id instead of plate

[Manason]

Dependent on Qbox-project/qbx_core#582

This turned into a more general overhaul as opportunities to delete code rather than convert it arose, although I tried my best to leave future refactoring to another PR.

• Replacing plate with sessionId. This is a stable identifier so that if plate changes, the player still has access to the same vehicle entity.
• moved the command code for giving keys entirely to the server. Changed the admin command for giving keys to be the same as the player one, but without the check that the admin already has the keys
• removed the admin command to remove keys. It doesn't seem super useful, and needed to be redone anyway
• removed backwards compatibility events for now. It's questionable if we want to support backwards compatibility in vehiclekeys, and these would need to be redone anyway.
• Removed some exports without a clear use case. It's easy to add to an API later, but once published we can't remove these exports.
• Exposing RemoveKeys as an export
• Removed code which pre-loads all of a player's owned vehicles as keys. This no longer makes sense as we can only give keys to physical entities in the world. Removing it shouldn't change behavior as when a player owned vehicle is spawned, the owner should be given keys.