SAML IdP Enhancements

[apshoemaker]

This PR allows for the provider to address the newly introduced additional parameters to the SAML Identity Provider within the Requested AuthnContext Constraints section including:

• Comparison (authn_context_comparison_type): includes validations ensuring one of Exact, Minimum, Maximum, or Better.
• AuthnContextClassRefs (authn_context_class_refs): includes a new type KeycloakSliceQuoted that follows the same pattern as KeycloakBoolQuoted to accomplish the same goal of ensuring that the collection is properly quoted for acceptance to the Keycloak API.
• AuthnContextDeclRefs (authn_context_class_decls): essentially same as above save for the parameter name.

Additionally, hopefully you will find that I have included tests that test for the presence of these newly created parameters. Please let me know if you have comments on code structure or quality and need adjustments to either for acceptance.

[apshoemaker]

@mrparkers is there anything that needs to be done here to get this PR merged? It would be nice to be able to stop using my forked version and move back to the official release. Thank you!

[apshoemaker]

@mrparkers very sorry for the severely delayed response here. I have updated my remote to remove this unnecessary dependency as well as rebase your upstream master branch in an attempt to eliminate merge conflicts given the time that has passed between additions. Please let me know if you see anything amiss that might prevent this PR from being merged. Thank you!

[dnic]

@apshoemaker @mrparkers I rebased these changes and undid a naming change on XmlSigKeyInfoKeyNameTransformer so the review is a lot shorter. New PR here: https://github.com/mrparkers/terraform-provider-keycloak/pull/703.

[mrparkers]

Closed in favor of #703