Add copy to new test format button for old test resources

Old QTI 1.2 test resources and Onyx QTI 2.1 resources are not automatically converted to the new format. For QTI 1.2 tests this is already possible, but the option is a bit hidden in the editor. For Onyx QTI 2.1 resources it can be done manually by exporting and re-importing as new resources. During the import the resources is recognized as QTI 2.1 and will get the new resource type.

It would make live simpler to have a convert button for old test resources directly in the test menu of the learning resource.