MM-20698: Add server support for getting SAML metadata and updating S… (#13311)

* MM-20698: Add server support for getting SAMl metadata and updating SAMl settings

model/config.go

@@ -1913,6 +1913,7 @@ type SamlSettings struct {
 
 	IdpUrl                      *string
 	IdpDescriptorUrl            *string
+	IdpMetadataUrl              *string
 	AssertionConsumerServiceURL *string
 
 	SignatureAlgorithm *string
@@ -1984,6 +1985,10 @@ func (s *SamlSettings) SetDefaults() {
 		s.IdpDescriptorUrl = NewString("")
 	}
 
+	if s.IdpMetadataUrl == nil {
+		s.IdpMetadataUrl = NewString("")
+	}
+
 	if s.IdpCertificateFile == nil {
 		s.IdpCertificateFile = NewString("")
 	}