Add support for partitioned session cookies

[bookernath]

Related issue with historical context: pallets/werkzeug#2797

Partitioned cookies are now supported in Werkzeug: pallets/werkzeug#2855

It would be nice to have first-class support for the flask session cookie using the Partitioned flag to provide support for Chrome's CHIPS and allow sessions to continue to work within iframes.

Example usage might be:

app.config['SESSION_COOKIE_SAMESITE'] = "None"
app.config['SESSION_COOKIE_SECURE'] = True
app.config['SESSION_COOKIE_PARTITIONED'] = True # add this?

[Josecespedesant]

Hi! I'd like to take a look into collaborate in this issue

I was going through the context of this issue and saw that implicitly if partitioned is set to true it should also set secure to true as mentioned here: https://github.com/pallets/werkzeug/pull/2855/files#diff-cd95d3a95564f3230d4875ac34fc9d039856b033c6b1430d5d3cc864f87cf89aL1300

Would that be the case for here as well?

[davidism]

Yes, but you shouldn't need to do anything extra for that, it's already how it's implemented, as you've linked to.