[CLI] Performance Testing Tool

This MR extends the CLI with a command to perform performance tests to measure network bandwidth/messages per second:

$ drasyl perf --help
Tool for measuring network performance. A specified number of messages per second of the desired
size are sent to another node over a defined period of time. The amount of transferred data, the
bitrate, as well as the number of lost and (out of order) delivered messages, are recorded.

Usage:
  drasyl perf [flags]

Flags:
-c,--client <publicKey>      Runs in client mode, connecting to <publicKey>. If not set, runs in
                             server mode.
   --direct                  Client: Wait for direct connection before performing the test
-h,--help                    Show this help.
   --mps <count>             Client: Messages per second (default: 100)
   --reverse                 Client: Run in reverse mode (server sends, client receives)
   --size <bytes>            Client: Messages size (default: 850)
   --time <seconds>          Client: Time in seconds to transmit for (default: 10)
-v,--verbose <level>         Sets the log level (off, error, warn, info, debug, trace; default:
                             warn)

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https://sonarcloud.io/dashboard?branch=perf&id=org.drasyl%3Aparent