Add minetest.spawn_falling_node(pos) (#5339)

* Add minetest.spawn_falling_node(pos)

* lua_api.txt: Add minetest.spawn_falling_node(pos)

* Update minetest.spawn_falling_node(pos)

builtin/game/falling.lua

@@ -118,6 +118,20 @@ local function spawn_falling_node(p, node)
 	end
 end
 
+function core.spawn_falling_node(pos)
+	local node = core.get_node(pos)
+	if node.name == "air" or node.name == "ignore" then
+		return false
+	end
+	local obj = core.add_entity(pos, "__builtin:falling_node")
+	if obj then
+		obj:get_luaentity():set_node(node)
+		core.remove_node(pos)
+		return true
+	end
+	return false
+end
+
 local function drop_attached_node(p)
 	local nn = core.get_node(p).name
 	core.remove_node(p)