/locate closest player structures

Sometimes, we build something in a random place and do not remember the coordinates. Then we completely lose it and cannot find it. If we can estimate a coordinate near it, then we can use 
'/locate structure player_built'.

This will allow us to locate the nearest thing altered by a player. We could also choose a 'block' after 'player_build', so it locates that block placed by a player, in case someone else placed something closer to you and you do not find the correct thing.