Allow edition in the new UI

This make everything slow as hell and prevent to quickly save.

https://tools.ietf.org/html/draft-ietf-httpbis-rfc6265bis-02

We choose Lax and not Strict so that we can open links to ERP5 from
external applications and so that OAuth Logins work. Implementing the
"two cookies, one for read one for write" approach suggested in
https://tools.ietf.org/html/draft-ietf-httpbis-rfc6265bis-02#section-8.8.2
would be too big change at this point.

SameSite=None breaks the compatibility with some browser versions.
https://www.chromium.org/updates/same-site/incompatible-clients

Allow python's cryptographically secure pseudorandom number generator for usage in restricted python and use it where it makes sense.

This also change the API of `Person_generatePassword` which no longer allow to control the number of letters and numbers.

/reviewed-on nexedi/erp5!847

This script no longer allow to control the number of letters and digit

Using same method as python 3.6's secrets module and a bit longer token
that what python currently recommends, since we were using very very
long tokens until now (so that it does not look like a "regression")

- use system random
- generate longer password with a larger space

API change in an incompatible way, it's no longer possible to control
the number of alpha and numeric. This was reducing a lot the number of
combinations, so it's better to break so that callers stop generating
too weak passwords.

to make the difference with other fields more visible

If we rename a script used as external validator, we don't have way of detecting that this script might be used, so add to the "static checks" a check that for every field referencing an external validator, this validator can actually be traversed.

/reviewed-on nexedi/erp5!1031

Check that script exists.

Like a real-world user.

__ac_name & __ac_password are only useful to get a cookie, so only use them
when the test is actually expecting a cookie.

One inline javascript snippet less.

ZODB Components: Preparation of erp5_base migration from FS: Fix pylint no-name-in-module on newTempXXX (04b49859).

Change upgrader internal API to use `filter_dict` instead of `filter`
which is a builtin.
Remove a lot of unused code in extensions

/reviewed-on nexedi/erp5!1014

ZODB Components: Preparation of erp5_base migration from FS: Fix pylint no-name-in-module on newTempXXX (04b49859).