New entity NBT Tags: "DiesWithMount:" & "DiesWithPassenger:"

These two new entity NBT tags allow for entities riding or being ridden to die if their rider/passenger is killed, which overrides other tags like NoAI. If set to 1, the passenger/mount dies with the rider/passenger, while 0 is the default. These NBT tags would allow for complex riding entities that could be extremely useful in mapmaking and in general.

For example, imagine a skeleton jockey that dies when either one is killed. Or instead, a creeper riding a baby zombie, that dies together only if the baby zombie is killed. One can even make an entity pillar of 50 villagers, that all die if one is killed. The possibilities this allows for would be huge for mapmaking, and a quality of life change for command makers, as they do not have to rely on datapacks instead to remove them.