Use browser 2020 recommendations for SameSite cookie rules

[summercms]

Discussion found here: #4752

Basically done the following:

1. Removed the SameSite = null as default. Under new rules this will cause an issue (see point 2).

2. SameSite = blank. Under new rules will become SameSite = None.

3. Cookies are made up of two main groups First-party and Third-party.

3.a). First-party cookies are set to strict or lax. Strict has an extra layer of security and I have been running October websites between 1-2 years will zero problems with Strict. (Our company has over 300 October websites, so we have tested it in a big'ish trail for over a year).

For new websites the default will be set to strict.

3.b). Third-party cookies are set to SameSite None and Secure true.

Testing guide

First-Party uses flag: chrome://flags/#same-site-by-default-cookies

Third-Party uses flag: chrome://flags/#cookies-without-same-site-must-be-secure

Thoughts

Maybe need to update October's min php version to 7.3 or above with regards to SameSite support.

---

Note: Issue with Windows 10 and SameSite Google Chrome V80, users need to install KB4534273

See here for link: https://support.microsoft.com/en-gb/help/4534273/windows-10-update-kb4534273

[github-actions]

This pull request will be closed and archived in 3 days, as there has been no activity in the last 30 days.

• If this is still being worked on, please respond and we will re-open this pull request. - If this pull request is critical to your business, consider joining the Premium Support Program where a Service Level Agreement is offered.

[github-actions]

This pull request will be closed and archived in 3 days, as there has been no activity in the last 30 days.
If this is still being worked on, please respond and we will re-open this pull request.
If this pull request is critical to your business, consider joining the Premium Support Program where a Service Level Agreement is offered.

[github-actions]

This pull request will be closed and archived in 3 days, as there has been no activity in the last 60 days.
If this is still being worked on, please respond and we will re-open this pull request.
If this pull request is critical to your business, consider joining the Premium Support Program where a Service Level Agreement is offered.

[Eoler]

This one is getting back into action on July 14: https://blog.chromium.org/2020/05/resuming-samesite-cookie-changes-in-july.html

[github-actions]

This pull request will be closed and archived in 3 days, as there has been no activity in the last 60 days.
If this is still being worked on, please respond and we will re-open this pull request.
If this pull request is critical to your business, consider joining the Premium Support Program where a Service Level Agreement is offered.

[summercms]

Quick update: The browsers have been rolling this out for a few weeks now, see more info here: https://www.chromium.org/updates/same-site

Aug 11, 2020
The target rollout population has been increased to 100% of users on Chrome Stable versions 80 and above, and the actual proportion of users with the new behavior enabled is now ramping up to 100% gradually. Users will receive the new behavior when they restart Chrome.

@LukeTowers @daftspunk

Request to add this pr as the rollout is now confirmed and in full swing.

[summercms]

Please see new pr here: #5293