Added the metadata url as an attribute on the IDP in the keycloak saml configuration which then propagates through to the DefaultSamlDeployment where it is used on the construction of the SamlDescriptorPublicKeyLocator thereby allowing support for ADFS or other IDP which uses a path that is different to the Keycloak IDP.
To make this work when testing with ADFS a change was made to SamlDescriptorIDPKeysExtractor because it would not extract keys from metadata which contained the EntityDescriptor as the root element. The solution was to change the xpath expression in SamlDescriptorIDPKeysExtractor so that it does not require a wrapping EntitiesDescriptor but instead loads all EntityDescriptors located in the document. This allows it to handle a single EntityDescriptor or multiple descriptors wrapped in an EntitiesDescriptor in the same xpath expression. A unit test SamlDescriptorIDPKeysExtractorTest has been added which validates that keys can be loaded in both scenarios.
Show expected URI and received URI in error message. Also makes the logging behavior of 'handleSamlResponse' the same as 'handleSamlRequest' since that method already shows the expected and received URI.
Updated schema schema for keycloak-saml.xml (added documentation, set
up enumeration instead of free string where applicable per documentation)
and updated existing keycloak-saml.xml files with schema reference.
Client adapter configuration was updated to support for customization
of HttpClient used for key retrieval similarly to OIDC. Further, it is
now possible to specify several static public keys for signature
verification in saml-client.xml.
