Transfer PasswordCSVReader tests to CSVPassword tests

CSVPassword is part of the new CSV parser for passwords, responsible
for parsing data rows. To ensure a smooth transition from the old CSV
parser -- PasswordCSVReader -- to the new one, relevant test cases
from PasswordCSVReader's test are being copied to CSVPassword's test.

The CL also adds some minor improvements to the test (fixing the test
name, adding const where it makes sense).

Bug: 934326
Change-Id: I5ad975765e74c71cdbe887dc3987c718d72af1a1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1920161
Commit-Queue: Vaclav Brozek <vabr@chromium.org>
Reviewed-by: Jan Wilken Dörrie <jdoerrie@chromium.org>
Cr-Commit-Position: refs/heads/master@{#716220}