Add some controllers + tests

This matches what is used in `modules/core/www/frontpage_config.php` for the classic UI.

This is now combined with the "SAML 2.0 IdP" enabled/disabled flag
which was a bit lonely before, as it's the only flag of its type.

A new one is in the making but it's completely different.

Hook 'metadata_hosted' and 'frontpage' are no longer called so do
not register hooks for them. Update the docs. Remove useless call
to configpage hook on admin module Test page (likely a copy-paste
error).

The metadata endpoint requires an entityID, not authsource to find
the corresponding IdP. Which makes sense because that is the unique
identifier - different IdPs can make use of the same backend auth
source.

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

This commit consists of patches automatically generated for this project on https://scrutinizer-ci.com

* 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