`\r` and `\n` arriving in separate chunks breaks line separator detection

[alecmev]

• Operating System: Any
• Node Version: Any
• NPM Version: Any
• csv-parser Version: 3.0.0

Expected Behavior

The assert in the repro passes.

Actual Behavior

The assert in the repro fails.

How Do We Reproduce?

import { deepStrictEqual } from 'node:assert';
import { Readable } from 'node:stream';

import csvParserFactory from 'csv-parser';

deepStrictEqual(
  await Readable.from(["foo\r", "\nbar\r\n", "baz\r\n"])
    .pipe(csvParserFactory())
    .toArray(),
  await Readable.from(["foo\r\n", "bar\r\n", "baz\r\n"])
    .pipe(csvParserFactory())
    .toArray(),
);

Cause

This happens because csv-parser is fine with nextChr being null when this.state.first is true. Instead it should wait until there's at least one more byte or the input stream is closed.