Consider using SdkHttpConfigurationOption over default akka-http connection settings

[matsluni]

Currently, this library uses the default ways to configure akka-http, either via application.conf or via the optional connectionPoolSettings. The AWS Java V2 SDK has its own way to configure the http clients, additionally with AWS Service specific defaults.

In #226 (comment) it was discussed to use the AWS SDK specific ways to configure the underlying akka-http client:

I understand right now that configuration is done via the normal methods of configuration i.e typesafe config library, but what are your thoughts about changing that to use the attributeMap? Asking because I see some specific clients configuring specific options like KinesisHttpConfigurationOptions and you can find other examples here
Maybe we should honor those...

If we would allow this, we would need to make sure, that this happens in a backward compatible way. So, that people, which are already use the optional connectionPoolSettings are not surprised with different configs coming from the new AWS specific config.