Fix debug startup netty log output

[Malinskiy]

Is your feature request related to a problem? Please describe.
During startup adam prints a huge log:

D 01:12:08.749 [main] <i.n.u.i.logging.InternalLoggerFactory> Using SLF4J as the default logging framework
D 01:12:08.750 [main] <io.netty.util.NetUtil> -Djava.net.preferIPv4Stack: false
D 01:12:08.750 [main] <io.netty.util.NetUtil> -Djava.net.preferIPv6Addresses: false
D 01:12:08.751 [main] <io.netty.util.NetUtilInitializations> Loopback interface: lo (lo, 0:0:0:0:0:0:0:1%lo)
D 01:12:08.759 [main] <i.netty.util.internal.PlatformDependent0> -Dio.netty.noUnsafe: false
D 01:12:08.760 [main] <i.netty.util.internal.PlatformDependent0> Java version: 15
D 01:12:08.760 [main] <i.netty.util.internal.PlatformDependent0> sun.misc.Unsafe.theUnsafe: available
D 01:12:08.760 [main] <i.netty.util.internal.PlatformDependent0> sun.misc.Unsafe.copyMemory: available
D 01:12:08.760 [main] <i.netty.util.internal.PlatformDependent0> java.nio.Buffer.address: available
D 01:12:08.762 [main] <i.netty.util.internal.PlatformDependent0> direct buffer constructor: unavailable
...

Describe the solution you'd like
By default, this shouldn't happen

[Malinskiy]

Due to the complexity of slf4j logging configuration depending on the actual implemention, this will depend on the user of adam. (This makes sense because only a final user of adam knows what they want to log).

For completeness sake here is a logback classic config example for removing the debug output above:

<configuration>
  <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
    <encoder>
      <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
    </encoder>
  </appender>
  <root level="DEBUG">
    <appender-ref ref="STDOUT" />
  </root>
  <logger name="io.netty" level="error"/>
  <logger name="io.vertx" level="error"/>
</configuration>