lwt: Add missing functions to utils/UUID_gen.hh
lwt: Add missing functions to utils/UUID_gen.hh

Some lwt related code is missing in our UUID implementation. Add it.

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