Support JSON Lines encoder for a stream response

JSON Lines is another JSON serialization format that can send a stream of JSON data. Currently, Armeria only supports JSON Text sequences format using JsonTextSequences. It would be nice to add a decoder that converts a stream of Java plain objects to JsonLines format.

HttpResponse response = JsonLines.fromPublisher(StreamMessage.of(foo, bar));

As a separate issue, supporting annotation service is also useful for users.

@ProducesJsonLines
public Publisher<MyObject> jsonLines() {
	return StreamMessage.of(foo, bar)
}

[amitvc]

@ikhoon Can I please pick this issue ? I am also done with other 2 issues I am working on.

[amitvc]

Thanks @ikhoon . Thanks for the clarification.