Replace SimpleSAML_IdP* with namespaced version

lib/SimpleSAML/IdP.php

lib/SimpleSAML/IdP/IFrameLogoutHandler.php

lib/SimpleSAML/IdP/LogoutHandlerInterface.php

lib/SimpleSAML/IdP/TraditionalLogoutHandler.php

lib/SimpleSAML/Session.php

modules/adfs/lib/IdP/ADFS.php

modules/adfs/www/idp/prp.php

modules/consent/lib/Logout.php

modules/consent/www/logout.php

modules/core/www/idp/logout-iframe-done.php

modules/core/www/idp/logout-iframe-post.php

modules/core/www/idp/logout-iframe.php

modules/core/www/idp/resumelogout.php

modules/saml/lib/Auth/Source/SP.php

modules/saml/lib/IdP/SAML1.php

modules/saml/lib/IdP/SAML2.php

modules/saml/www/proxy/invalid_session.php

tests/lib/SimpleSAML/DatabaseTest.php

tests/lib/SimpleSAML/Metadata/MetaDataStorageSourceTest.php

tests/lib/SimpleSAML/Metadata/SAMLBuilderTest.php