result_view: Add static helper method to do the dispatch from select
result_view: Add static helper method to do the dispatch from select

Again, makes it easier to use the same optimization/technique at more than
one location.

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