test(seed): Add Test for Unique Challenge Titles (#17035)

Due to the recent problem with two challenges having the same title, I
added a check for unique titles to the test suite so that hopefully
won't happen again.

Addresses a comment in issue #16906, which was recently closed.

BREAKING CHANGE: None

Closes #16906

challengeTitles.js

@@ -0,0 +1,26 @@
+import _ from 'lodash';
+
+class ChallengeTitles {
+  constructor() {
+    this.knownTitles = [];
+  }
+  check(title) {
+    if (typeof title !== 'string') {
+      throw new Error(`Expected a valid string for ${title}, got ${typeof title}`);
+    } else if (title.length === 0) {
+      throw new Error(`Expected a title length greater than 0`);
+    }
+    const titleToCheck = title.toLowerCase().replace(/\s+/g, '');
+    const titleIndex = _.findIndex(this.knownTitles, existing => titleToCheck === existing);
+    if (titleIndex !== -1) {
+      throw new Error(`
+    All challenges must have a unique title.
+
+    The title ${title} is already assigned
+    `);
+    }
+    this.knownTitles = [ ...this.knownTitles, titleToCheck ];
+  }
+}
+
+export default ChallengeTitles;