Break up the find_value into 2 parts (with get_value).

Break up the find_value into 2 parts (with get_value).

To better support multiple values per key, the old find_value request is
broken up into find_value, which doesn't stop when it finds a node with
values but just records the number of values the node has, and
get_value, which queries the found nodes that have values to retrieve
them.