Normal fireballs can use animated textures, but dragon fireballs cannot

Relates to: MC-260287 MC-269125 MC-277501 MC-277748 MC-278166 MC-278450

The bug

It is possible to assign animated textures to both small fireballs (blazes, dispensers) and large fireballs (ghasts). However, for some reason, it is not possible to do so for the ender dragon's fireball projectile.

How to reproduce

A resource pack that retextures all kinds of fireballs is attached to this ticket.

1. Download and apply

2. /summon minecraft:small_fireball ~-2 ~2 ~

3. /summon minecraft:fireball ~ ~2 ~

4. /summon minecraft:dragon_fireball ~2 ~2 ~

Expected results

All three would appear animated.

Actual results

Only two out of three appear animated.

How to fix

The fix is simple - the game just needs to load this texture from an atlas, rather than directly as an entity texture.

The cheap solution would be to add it to the blocks/items atlas. More preferably, an atlas for entity textures could be created, and the dragon fireball loaded from it. Existing textures could be moved there as well, such as those for item frames (MC-200946), conduits, enchanting tables and bells, which are currently in the blocks/items atlas. We could also merge the existing atlases for beds, chests, shulker boxes and signs into this so the game has to generate less atlases at startup.