Change item despawn time so that it is dependent on player render distance

Currently, playing with a high render distance creates a disadvantage for players who are trying to retrieve dropped items after death, because it will lead to chunks loading dropped items much sooner than normal. Playing with a high render distance does not generally allow players to navigate to their death site more quickly, but once they approach within render range, their equipment despawn timer starts regardless, and there may not be much of an opportunity to retrieve these items before they disappear. On the whole, this makes preset despawn timers seem counterintuitive from a game design perspective.

This would be a gamerule that is easily implementable in single-player. In multi-player, the despawn time would likely just be associated to the default render distance of the server regardless of whether an individual player lowers theirs.