Support ndjson

[texodus]

• Adds NDJSON support to the perspective.table() constructor, via the format option.
• Adds view.to_ndjson() serialization method.

const table = await perspective.table(`{"x": 1}\n{"x": 2}`, {format: "ndjson"});
const view = await table.view();
const ndjson = await view.to_ndjson();

[timkpaine]

just noting that, annoyingly, ndjson and jsonl are both widely used names for the same thing, as it has not been standardized. I support using ndjson as the api as this is what polars does, but might want to link both in the docs.

Also the old ldjson 😮‍💨 https://en.wikipedia.org/wiki/JSON_streaming#LDJSON, arrow doesnt link to any but it does use this language.