dht: Introduce dht::partition_range_vector and dht::token_range_vector
dht: Introduce dht::partition_range_vector and dht::token_range_vector

std::vector<dht::partition_range> and std::vector<dht::token_range> are
used in a lot of places, introduce dht::partition_range_vector and
dht::token_range_vector as the alias.

duarten/scylla,avikivity/scylla,raphaelsc/scylla,raphaelsc/scylla,scylladb/scylla,scylladb/scylla,avikivity/scylla,scylladb/scylla,raphaelsc/scylla,duarten/scylla,avikivity/scylla,duarten/scylla,scylladb/scylla