sstring: add data() methods
sstring: add data() methods

Traditional in string types.

avikivity/seastar,syuu1228/seastar,dreamsxin/seastar,cloudius-systems/seastar,scylladb/seastar,dreamsxin/seastar,syuu1228/seastar,dreamsxin/seastar,scylladb/seastar,avikivity/seastar,kjniemi/seastar,cloudius-systems/seastar,kjniemi/seastar,syuu1228/seastar,cloudius-systems/seastar,avikivity/seastar,kjniemi/seastar,scylladb/seastar