Stdout JSON output should allow NDJSON format to be produced

[willsalt-sl]

Feature Request

According to User Story #440, when a user specifies JSON output but does not specify an output file, output should be to stdout in NDJSON format rather than regular JSON.

When the stdout feature was implemented, this was not done.

Steps to reproduce

1. Run a command that specifies JSON output to stdout

Note that normal JSON output is produced. We require NDJSON output to be produced.

[pdaulbyscottlogic]

should this be a feature to add NDJSON as a separate output option (in addition to CSV and JSON)

[willsalt-sl]

I had a discussion with @ms14981 earlier about the distinction between bugs and features - it's a fine dividing line and arguably is just a question of phrasing. I would class this as a bug, though, because we had a feature request, we closed that feature request, but we didn't implement part of it. The fact that we said we had done X but the system does not, in fact, do X, means that it is in my opinion a bug.

Whether we resolve it by adding NDJSON as a separate output format is a question of implementation more than anything else, as long as we meet the requirement that when JSON output is selected and output is to standard output, NDJSON output is what the program produces.

[pdaulbyscottlogic]

FasterXML/jackson-future-ideas#33 (comment)