managed_bytes: add cast to mutable_view
managed_bytes: add cast to mutable_view

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