Fix "SLEEP" and "STOP_SLEEPING" animations for 1.14 and 1.15 (#2029)
These now both fully work as they used to, allowing an NPC (or any Player entity) to go into a sleeping animation without requiring a bed (which is a bug introduced in the one of the recent MC updates). Fully tested and working in 1.15, presumed working for 1.14 as most things work the same. Not ported to 1.13 as I'm less confident on whether things are equivalent that far back. (commit: 72c7332)
