Abstract listener client and message sender interfaces

[c-w]

Unlike the streaming client, the listener client and message sender interfaces are concrete in the types of arguments that all of its implementations receive (e.g. port and host). However, there are potential implementations for which these arguments won't be appropriate (e.g. a docker-client based message sender). As such, this pull request refactors the constructor signatures to follow the config-dictionary pattern. This will also enable dynamic creation and configuration of the classes in the future.

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