Use storage_path on ctest submit for validation

When attempting to validate an HTTP submission use the `storage_path` helper
to turn the filename which starts at the inproess folder, `inprocess/<>.xml`,
to a full path.  This should not affect the path given directly to the
submission:validate artisan command.

app/cdash/include/ctestparser.php

@@ -185,7 +185,7 @@ function ctest_parse($filehandle, string $filename, $projectid, $expected_md5 =
     // If validation is enabled and if this file has a corresponding schema, validate it
     if (((bool) config('cdash.validate_xml_submissions')) === true && isset($schema_file)) {
         try {
-            SubmissionUtils::validate_xml($filename, $schema_file);
+            SubmissionUtils::validate_xml(storage_path("app/".$filename), $schema_file);
         } catch (CDashXMLValidationException $e) {
             foreach ($e->getDecodedMessage() as $error) {
                 Log::error("Validating $filename: ".$error);