Support for loading JSON Lines

[gfissore-rai]

As of now we have rai load-json to load JSON files. It would be very useful for certain datasets to also have something like rai load-jsonl (or rai load-json --lines).

[billscheidel-rai]

Note: This issue has been migrated to https://relationalai.atlassian.net/browse/RAI-8074.

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