Simple benchmark

[acerone85]

This MR introduces a new binary simple-benchmark implemented in a separate crate.
The commands provided are:

• spammer (behaves as the spammer implemented in simple_spammer
• listener (behaves as the listener implemented in simple_listener, with some tweaks to handle lost connections.
• benchmark. Runs a spammer and listener in parallel for a determined amount of time (default 30 seconds), and in the case a output file is specified, statistics such as median, mean, and std-dev of latencies are gathered and printed to screen

to test the simple-benchmark, try:

make run-dsn

in one shell, and

RUST_LOG=info cargo run --bin simple-benchmark -- benchmark --tx-output $PATH_TO_CSV_RESULTS_FILE --run-for 60

in another

[github-actions]

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