Player sleeping in bed has no gravity server side

When you teleport a player upwards when they are sleeping in a bed, the sleeping player floats in the air but on the client view of the sleeping player, they fall downwards but keep being teleported to the server's position.

Steps to reproduce:
1. Start a LAN Server.
2. Get a player to join and sleep in a bed
3. Teleport the sleeping player upwards by doing "/tp <PlayerName> ~ ~5 ~"

The bug can be fixed by making the sleeping player have gravity server-side.