Package: Validate challenges on test (#17216)

This PR allows us to validate the schema during test.

It also removes some cruft from the seed files and ensures only the required data is packaged and consumable, reducing the package weight somewhat.

getChallenges.js

@@ -2,6 +2,7 @@
 // no import here as this runs without babel
 const fs = require('fs');
 const path = require('path');
+const omit = require('lodash/omit');
 
 const hiddenFile = /(^(\.|\/\.))|(.md$)/g;
 
@@ -52,6 +53,24 @@ module.exports = function getChallenges(challengesDir) {
       challengeSpec.fileName = data.file;
       challengeSpec.superBlock = superInfo.name;
       challengeSpec.superOrder = superInfo.order;
+      challengeSpec.challenges = challengeSpec.challenges
+        .map(challenge => omit(
+          challenge,
+          [
+            'betaSolutions',
+            'betaTests',
+            'hints',
+            'MDNlinks',
+            'null',
+            'rawSolutions',
+            'react',
+            'reactRedux',
+            'redux',
+            'releasedOn',
+            'translations',
+            'type'
+          ]
+        ));
       return challengeSpec;
     });
 };