Addition of EntityType TagKey

[ShaneBeee]

Is your feature request related to a problem?

not really a problem other than its missing

Describe the solution you'd like.

I would like to suggest the addition of an EntityType TagKey in the io/papermc/paper/registry/keys/tags/ package.
There are TagKeys for other things such as BlockType, ItemType, Biome, but nothing for EntityType.

Describe alternatives you've considered.

Bukkit has the Tag class, but I see Paper wants to transition to its own tag system.

Other

No response