storage_service: Introduce run_with_write_api_lock helper
storage_service: Introduce run_with_write_api_lock helper

It is useful to run code on cpu zero with the api lock.

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