Certain sounds are missing sound event name

Certain sounds that used to be able to be played through /playsound from 1.8 and earlier snapshots are in game but unplayable after the change to the new sound format due to there being no sound event name that uses the sound. The sounds still exist in the game since they are listed in assets>indexes>1.9.json.

The following sounds are no longer playable in any form (listed by what they are originally called):

• note.pling
• note.bass
• mob.bat.loop
• mob.ghast.affectionate_scream
• mob.wolf.howl
• mob.cat.hiss

This may have occurred as there is no in game event that triggers the sound and thus no sound name to play through /playsound. However, there are other sounds that DO exist even though they are not used in game:

• format: new sound name (old sound name)
• entity.zombie.attack_iron_door (mob.zombie.metal)
• entity.silverfish.step (mob.silverfish.step)
• entity.endermite.step (mob.silverfish.step)