feat: Add support for sameSite field

[freddy77]

Summary

Recent browsers (and HTTP) added sameSite setting to limit cross site attacks.
Add support for exporting this property from Firefox and Chrome and to export to csv and cookie-editor format.
Also extract new session and hostOnly properties for cookie-editor format.
Tested on Firefox, Chrome and Chromium.

Fixes #

Checklist

• Pull request targets the main branch
• All CI checks pass (lint, test, build)
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)
• go.mod directive remains go 1.20 (do not bump)

[moonD4rk]

Thanks for this! I tested the branch on Windows against 12 Chromium forks and 3 Firefox profiles — the enum mappings are right (Firefox 0 = explicit SameSite=None, 256 = unset), and cookie output is identical to main apart from the new field.

Two things before merge.

1. CSV assertions are stale

CookieEntry.SameSite adds a CSV column, and 3 tests still expect the old header:

go test ./output/...

• output/output_test.go:109 — add "same_site" to the expected header
• output/output_test.go:116 — add "" to the expected row
• output/reflect_test.go:57 — add "same_site" to the CookieEntry case
• output/reflect_test.go:90 — add "" to the CookieEntry case

2. Emit "unspecified" instead of an empty string

For cookies with no SameSite attribute (-1 on Chromium, 256 on Firefox) the field is currently "", which omitempty then drops entirely — so an importer can't tell "no SameSite attribute" from "unknown". It's not a rare case: 101 of 277 Chrome cookies on my test box.

"unspecified" is the value the WebExtensions SameSiteStatus enum uses for exactly this. It also gives the case -1: / case 256: branches something to do — right now they're empty and behave the same as having no case at all.

[freddy77]

Updated. I hope to have addressed everything correctly.