Feat: add new Markdown parser (#39800)

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

curriculum/challenges/english/10-coding-interview-prep/rosetta-code/vector-cross-product.md

@@ -1,54 +1,41 @@
 ---
-title: Vector cross product
 id: 594810f028c0303b75339ad2
+title: Vector cross product
 challengeType: 5
 forumTopicId: 302342
 ---
 
-## Description
-<section id='description'>
+# --description--
 
 A vector is defined as having three dimensions as being represented by an ordered collection of three numbers: (X, Y, Z).
-</section>
 
-## Instructions
-<section id='instructions'>
+# --instructions--
 
-Write a function that takes two vectors (arrays) as input and computes their cross product. Your function should return <code>null</code> on invalid inputs such as vectors of different lengths.
-</section>
+Write a function that takes two vectors (arrays) as input and computes their cross product. Your function should return `null` on invalid inputs such as vectors of different lengths.
 
-## Tests
-<section id='tests'>
+# --hints--
 
-```yml
-tests:
-  - text: dotProduct should be a function.
-    testString: assert.equal(typeof crossProduct, 'function');
-  - text: dotProduct() should return null.
-    testString: assert.equal(crossProduct(), null);
-  - text: crossProduct([1, 2, 3], [4, 5, 6]) should return [-3, 6, -3].
-    testString: assert.deepEqual(res12, exp12);
-
-```
-
-</section>
-
-## Challenge Seed
-<section id='challengeSeed'>
-
-<div id='js-seed'>
+dotProduct should be a function.
 
 ```js
-function crossProduct(a, b) {
-
-}
+assert.equal(typeof crossProduct, 'function');
 ```
 
-</div>
+dotProduct() should return null.
 
+```js
+assert.equal(crossProduct(), null);
+```
 
-### After Test
-<div id='js-teardown'>
+crossProduct([1, 2, 3], [4, 5, 6]) should return [-3, 6, -3].
+
+```js
+assert.deepEqual(res12, exp12);
+```
+
+# --seed--
+
+## --after-user-code--
 
 ```js
 const tv1 = [1, 2, 3];
@@ -57,13 +44,15 @@ const res12 = crossProduct(tv1, tv2);
 const exp12 = [-3, 6, -3];
 ```
 
-</div>
+## --seed-contents--
 
-</section>
+```js
+function crossProduct(a, b) {
 
-## Solution
-<section id='solution'>
+}
+```
 
+# --solutions--
 
 ```js
 function crossProduct(a, b) {
@@ -82,7 +71,4 @@ function crossProduct(a, b) {
     (a[0] * b[1]) - (a[1] * b[0])
   ];
 }
-
 ```
-
-</section>