Imports of nats-bench command

PathSynopsis
flagPackage flag implements command-line flag parsing.
fmtPackage fmt implements formatted I/O with functions analogous to C's printf and scanf.
github.com/nats-io/nats.goA Go client for the NATS messaging system (https://nats.io).
github.com/nats-io/nats.go/bench
logPackage log implements a simple logging package.
osPackage os provides a platform-independent interface to operating system functionality.
syncPackage sync provides basic synchronization primitives such as mutual exclusion locks.
timePackage time provides functionality for measuring and displaying time.