FreeType vs fontations path loading in CI

For a variety of scenarios, including VFs with overlaps

For reference, https://skia-review.googlesource.com/c/skia/+/740176/1/gm/fontations_ft_compare.cpp. I believe we already have code that does something similar so really just to confirm we agree on what constitutes a diff. Also shows some potential test strings.

We should be able to share test fonts and strings via https://chrome-infra-packages.appspot.com/ as @drott will update to use https://chromium.googlesource.com/experimental/chromium/src/+/refs/tags/68.0.3404.0/docs/cipd.md so we can use the same `(test string, font)` pairs. That has value because we have some ideas about how to build a decent smoke test.