Modern Spawn Eggs Pre-Flattening Backport

The modern 1.21.5 spawn egg textures backported to pre-flattening versions (1.8-1.12.2) The flattening (1.13) was the update that reworked item IDs, including giving each spawn egg a unique model. On versions before this all spawn eggs use the same model, meaning **OPTIFINE IS REQUIRED** to make use of it's Custom Item Texture feature to enable unique spawn eggs. Ignore any "Made for a newer version of Minecraft" errors that may appear in the resource pack selector, as long as you are within 1.8-1.12.2 with Optifine the pack will work.