Closes: #1683
(cherry picked from commit d3e728fa)

Co-authored-by: Thijs Kinkhorst <thijs@kinkhorst.com>

strftime is deprecated and will be removed in PHP 9. SSP 2.0 is our
chance to change this format as it's exposed to installers of SSP.

The approch is to keep it simple and just change the format to PHP's
built in date() function which remains supported. Also we do not try
to localize the logging date/timestamps anymore. This matches the syslog
approach that this format tried to mimic. We are using the day without
leading zeroes now also to be a bit closer to how syslog does it.

We remove the functionality to see all auth sources and to test them
publically. Testing the auth sources can be done inside the admin
module.

Added is a configuration option that allows the administrator to specfy
another place to redirect to for people who land on the front page.

Now also considers any attributes.po in the configured theme, if any.
Makes the attributes.extradictionary config setting obsolete.

We could use it everywhere, but it's better to reduce the already big
amount of configuration options the admin is confronted with than the
small problem this option solves.

* Conform SAML2INT; check AuthnRequest signature unless specifically disabled

* Migrate email utils to non-static

* Migrate http utils to non-static

* Migrate net utils to non-static

* Migrate random utils to non-static

* Migrate system utils to non-static

* Migrate time utils to non-static

* Migrate xml utils to non-static

* Upgrade notes

* Update test-framework

* Fix tests

* Migrate array utils to non-static

* Migrate attribute utils to non-static

* Migrate auth utils to non-static

* Migrate config utils to non-static

* Migrate crypto utils to non-static

* Raise coverage

* Fix rebase issue