[IMP] web: warn admin on login if their password is "admin"
[IMP] web: warn admin on login if their password is "admin"

* We want to limit the obtrusiveness of the mechanism & at the same
time show the warning immediately, so send the warning through a
private channel between the superuser and the admin user rather than
the regular mail.thread's message_post which would likely send the
warning though email.
* Ignore issue when the request comes from a "private" IP (likely a
local dev box where it doesn't matter).
* Only check for "admin" on the admin user: passwords created manually
are already length-checked (required) and strength-checked (visual
indicator).

Task 31122

Supersedes #22428

closes odoo/odoo#33254

Signed-off-by: Xavier Morel (xmo) <0f311f41b2be8e2b5de98776566d712cdc154ca4@odoo.com>
ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo