sharded: declare internal::sharded_parallel_for_each earlier
sharded: declare internal::sharded_parallel_for_each earlier

Declare sharded_parallel_for_each earlier in the file
in preparation to defining a private sharded::sharded_parallel_for_each
method.

Signed-off-by: Benny Halevy <23c997c90eb8537635e9392d48e7af1bf1b2ca22@scylladb.com>

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