suggestion: investigate simpler CSV-parsing APIs

[`CsvParseStream()`](https://deno.land/std@0.205.0/csv/mod.ts?s=CsvParseStream) and [`parse()`](https://deno.land/std@0.205.0/csv/mod.ts?s=parse) in `std/csv` appear to be more complicated than needed. I think we could do the following:
- [ ] Create a `parseLine(line: string): string[]` which `CsvParseStream()` and `parse()` can use to parse each line.
- [ ] Require the piping of [`TextLineStream()`](https://deno.land/std@0.205.0/streams/mod.ts?s=TextLineStream) in the stream before `CsvParseStream()` so the duplicated logic can be offloaded.

I could be wrong with these, but it's worth the discussion. Other ideas to simplify these APIs are also welcome.

Related #2291