feat(server)!: oauth encryption algorithm setting (#6818)

* feat: add oauth signing algorithm setting

* chore: open api

* chore: change default to RS256

* feat: test and clean up

---------

Co-authored-by: Jason Rasmussen <jrasm91@gmail.com>

mobile/openapi/test/system_config_o_auth_dto_test.dart

@@ -66,6 +66,11 @@ void main() {
       // TODO
     });
 
+    // String signingAlgorithm
+    test('to test the property `signingAlgorithm`', () async {
+      // TODO
+    });
+
     // String storageLabelClaim
     test('to test the property `storageLabelClaim`', () async {
       // TODO