* Allow list of entity ids to be loaded to better support idpList

Certain metadata sources, like mdq, were don't support loading all metadata which
prevented them from being used with idplist. This change adds support for allowing
metadata sources to load a list of entities, allowing MDQ to be used for idp list.

When migrating to namespaces, this class had to change its name, as "Default" is a reserved keyword. However, that implies changing the file name as well. Currently, it doesn't load.

When externalizing the modules, we started to 'require' for example ext-krb5, where we used to only 'suggest' it.
That's when AppVeyor started to fail, since those extensions are not available and have proven to be hard to install..
This workaround should do the trick until we stop including those externalized modules in releases.

Properly set NameIDFormat on generation

Downgrade externalized modules to a version that doesn't hold BC-breaking Webmozart-assertions

Fixes https://github.com/simplesamlphp/simplesamlphp/issues/1135

* updated catalan translations

* IDP configurable AuthnContextClassRef/AuthnContextComparison

* Add a few namespaces