Feat: add new Markdown parser (#39800)

and change all the challenges to new `md` format.

curriculum/challenges/english/10-coding-interview-prep/rosetta-code/factorial.md

@@ -1,54 +1,63 @@
 ---
-title: Factorial
 id: 597b2b2a2702b44414742771
+title: Factorial
 challengeType: 5
 forumTopicId: 302263
 ---
 
-## Description
-<section id='description'>
+# --description--
+
 Write a function to return the factorial of a number.
+
 Factorial of a number is given by:
-<pre>
-<big>n! = n * (n-1) * (n-2) * ..... * 1</big>
+
+<pre><big>n! = n * (n-1) * (n-2) * ..... * 1</big>
 </pre>
+
 For example:
+
 <ul>
   <li><code>3! = 3 * 2 * 1 = 6</code></li>
   <li><code>4! = 4 * 3 * 2 * 1 = 24</code></li>
 </ul>
-<strong>Note:</strong> <code>0! = 1</code>
-</section>
 
-## Instructions
-<section id='instructions'>
+**Note:** `0! = 1`
 
-</section>
+# --hints--
 
-## Tests
-<section id='tests'>
-
-```yml
-tests:
-  - text: <code>factorial</code> should be a function.
-    testString: assert(typeof factorial === 'function');
-  - text: <code>factorial(2)</code> should return a number.
-    testString: assert(typeof factorial(2) === 'number');
-  - text: <code>factorial(3)</code> should return 6.
-    testString: assert.equal(factorial(3), 6);
-  - text: <code>factorial(5)</code> should return 120.
-    testString: assert.equal(factorial(5), 120);
-  - text: <code>factorial(10)</code> should return 3,628,800.
-    testString: assert.equal(factorial(10), 3628800);
+`factorial` should be a function.
 
+```js
+assert(typeof factorial === 'function');
 ```
 
-</section>
+`factorial(2)` should return a number.
 
-## Challenge Seed
-<section id='challengeSeed'>
+```js
+assert(typeof factorial(2) === 'number');
+```
 
-<div id='js-seed'>
+`factorial(3)` should return 6.
+
+```js
+assert.equal(factorial(3), 6);
+```
+
+`factorial(5)` should return 120.
+
+```js
+assert.equal(factorial(5), 120);
+```
+
+`factorial(10)` should return 3,628,800.
+
+```js
+assert.equal(factorial(10), 3628800);
+```
+
+# --seed--
+
+## --seed-contents--
 
 ```js
 function factorial(n) {
@@ -56,14 +65,7 @@ function factorial(n) {
 }
 ```
 
-</div>
-
-
-</section>
-
-## Solution
-<section id='solution'>
-
+# --solutions--
 
 ```js
 function factorial(n) {
@@ -74,8 +76,4 @@ function factorial(n) {
   }
   return sum;
 }
-
-
 ```
-
-</section>