Support for draft-ietf-json-text-sequence

logstash should ingest JSON data in this form: https://datatracker.ietf.org/doc/draft-ietf-json-text-sequence/

Basically, that means `RS + JSON + LF`.

Since log stash already handles `JSON + LF`, a trivial parser could simply delete the leading RS character. A smarter one would use this to detect truncated JSON text and recover the following record, as described in the spec.