When downloading metadata, add a .xml extension

Closes: #1510

Co-Authored-By: Bart Langelaan <langelaanbart@gmail.com>

modules/saml/www/sp/metadata.php

@@ -47,4 +47,5 @@ $xml = $metaBuilder->getEntityDescriptorText();
 $xml = Metadata\Signer::sign($xml, $spconfig->toArray(), 'SAML 2 SP');
 
 header('Content-Type: application/samlmetadata+xml');
+header('Content-Disposition: attachment; filename="' . basename($sourceId) . '.xml"');
 echo($xml);

www/saml2/idp/metadata.php

@@ -36,6 +36,7 @@ try {
     $metaxml = \SimpleSAML\Metadata\Signer::sign($metaxml, $metaArray, 'SAML 2 IdP');
 
     header('Content-Type: application/samlmetadata+xml');
+    header('Content-Disposition: attachment; filename="idp-metadata.xml"');
 
     echo $metaxml;
     exit(0);