Count fluids by their type to avoid unnecessary reads in Entity#updateFluidHeightAndDoFluidPushing

[wuangg]

Avoid searching for chunk sections that don't only have non empty blocks, but also non empty fluids

[wuangg]

Since Fabric/Vanilla version of the method has the TagKey as a parameter, we would like to only check for the count of non-empty fluid states that have the same fluid TagKey to avoid unnecessary chunk section searches that do not have any fluid has the same TagKey as the parameter.

As for modded fluid/NeoForge version of the method, I will implement a counter for generic non-empty fluid states.

[wuangg]

Counter for generic non-empty fluid states has been implemented.