Add "application/jsonl" support alongside "application/x-ndjson" for streaming #36485

Spring Framework already supports the "application/x-ndjson" new line delimited JSON media type for streaming multiple JSON payloads in a streaming fashion.

Latest community developments seems to indicate that "application/jsonl" (JSON Lines) might supersede it in the future and is in the process of being standardized.

We should add "application/jsonl" to the well-known media types and ensure that it is supported alongside NDJSON in the Framework.