CL 72150 fixes #22352 by reverting the problematic parts of that CL
where the line number and column number were inconsistent with each other.
This CL adds back functionality to address the issue that CL 72150
was trying to solve in the first place. That is, it reports the starting
line of the record, so that users have a frame of reference to start with
when debugging what went wrong.

In the event of gnarly CSV files with multiline quoted strings, a parse
failure likely occurs somewhere between the start of the record and
the point where the parser finally detected an error.
Since ParserError.{Line,Column} reports where the *error* occurs, we
add a RecordLine field to report where the record starts.

Also take this time to cleanup and modernize TestRead.

Fixes #19019
Fixes #22352

Change-Id: I16cebf0b81922c35f75804c7073e9cddbfd11a04
Reviewed-on: https://go-review.googlesource.com/72310Reviewed-by: Ian Lance Taylor <iant@golang.org>