Cleaned up and added API for entity air supply, fixed oxygen being used in creative/spectator

this commit also includes respiration checks because it's cherry-picked
from api3/blocks, but respiration won't work until it's registered.

src/pocketmine/Player.php

@@ -1713,6 +1713,10 @@ class Player extends Human implements CommandSender, ChunkLoader, IPlayer{
 		return 0.0;
 	}
 
+	public function canBreathe() : bool{
+		return $this->isCreative() or parent::canBreathe();
+	}
+
 	public function checkNetwork(){
 		if(!$this->isOnline()){
 			return;