feat: add saml request to link to sessions (#9001)

# Which Problems Are Solved

It is currently not possible to use SAML with the Session API.

# How the Problems Are Solved

Add SAML service, to get and resolve SAML requests.
Add SAML session and SAML request aggregate, which can be linked to the
Session to get back a SAMLResponse from the API directly.

# Additional Changes

Update of dependency zitadel/saml to provide all functionality for
handling of SAML requests and responses.

# Additional Context

Closes #6053

---------

Co-authored-by: Livio Spring <livio.a@gmail.com>

internal/domain/saml_error_reason.go

@@ -0,0 +1,41 @@
+package domain
+
+import (
+	"github.com/zitadel/saml/pkg/provider"
+)
+
+type SAMLErrorReason int32
+
+const (
+	SAMLErrorReasonUnspecified SAMLErrorReason = iota
+	SAMLErrorReasonVersionMissmatch
+	SAMLErrorReasonAuthNFailed
+	SAMLErrorReasonInvalidAttrNameOrValue
+	SAMLErrorReasonInvalidNameIDPolicy
+	SAMLErrorReasonRequestDenied
+	SAMLErrorReasonRequestUnsupported
+	SAMLErrorReasonUnsupportedBinding
+)
+
+func SAMLErrorReasonToString(reason SAMLErrorReason) string {
+	switch reason {
+	case SAMLErrorReasonUnspecified:
+		return "unspecified error"
+	case SAMLErrorReasonVersionMissmatch:
+		return provider.StatusCodeVersionMissmatch
+	case SAMLErrorReasonAuthNFailed:
+		return provider.StatusCodeAuthNFailed
+	case SAMLErrorReasonInvalidAttrNameOrValue:
+		return provider.StatusCodeInvalidAttrNameOrValue
+	case SAMLErrorReasonInvalidNameIDPolicy:
+		return provider.StatusCodeInvalidNameIDPolicy
+	case SAMLErrorReasonRequestDenied:
+		return provider.StatusCodeRequestDenied
+	case SAMLErrorReasonRequestUnsupported:
+		return provider.StatusCodeRequestUnsupported
+	case SAMLErrorReasonUnsupportedBinding:
+		return provider.StatusCodeUnsupportedBinding
+	default:
+		return "unspecified error"
+	}
+}

internal/domain/saml_request.go

@@ -0,0 +1,10 @@
+package domain
+
+type SAMLRequestState int
+
+const (
+	SAMLRequestStateUnspecified SAMLRequestState = iota
+	SAMLRequestStateAdded
+	SAMLRequestStateFailed
+	SAMLRequestStateSucceeded
+)

internal/domain/saml_session.go

@@ -0,0 +1,9 @@
+package domain
+
+type SAMLSessionState int32
+
+const (
+	SAMLSessionStateUnspecified SAMLSessionState = iota
+	SAMLSessionStateActive
+	SAMLSessionStateTerminated
+)