chore: import upstream snapshot with attribution

tools/challenge-parser/parser/plugins/restore-directives.js

@@ -0,0 +1,32 @@
+const directive = require('mdast-util-directive');
+var toMarkdown = require('mdast-util-to-markdown');
+const { matches } = require('unist-util-select');
+const visit = require('unist-util-visit');
+
+function plugin() {
+  return transformer;
+
+  function transformer(tree) {
+    visit(tree, visitor);
+
+    function visitor(node, id, parent) {
+      // currently `remark-directive` seems to be ignoring containerDirectives
+      // but, assuming that will get fixed, we test for it anyway.
+      const isDirective =
+        matches('leafDirective', node) ||
+        matches('textDirective', node) ||
+        matches('containerDirective', node);
+
+      if (isDirective) {
+        parent.children[id] = {
+          type: 'text',
+          value: toMarkdown(node, {
+            extensions: [directive.toMarkdown]
+          }).trim()
+        };
+      }
+    }
+  }
+}
+
+module.exports = plugin;