util: allow specifying noexcept for noncopyable_function
util: allow specifying noexcept for noncopyable_function

With an additional template parameter it's possible to define
noncopyable_function template specializations with noexcept
function types.

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