Feat: add new Markdown parser (#39800)

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

curriculum/challenges/english/10-coding-interview-prep/project-euler/problem-5-smallest-multiple.md

@@ -1,50 +1,57 @@
 ---
 id: 5900f3711000cf542c50fe84
-challengeType: 5
 title: 'Problem 5: Smallest multiple'
+challengeType: 5
 forumTopicId: 302160
 ---
 
-## Description
-<section id='description'>
+# --description--
 
 2520 is the smallest number that can be divided by each of the numbers from 1 to 10 without any remainder.
 
 What is the smallest positive number that is evenly divisible by all of the numbers from 1 to `n`?
 
-</section>
+# --hints--
 
-## Instructions
-<section id='instructions'>
-
-</section>
-
-## Tests
-<section id='tests'>
-
-```yml
-tests:
-  - text: <code>smallestMult(5)</code> should return a number.
-    testString: assert(typeof smallestMult(5) === 'number');
-  - text: <code>smallestMult(5)</code> should return 60.
-    testString: assert.strictEqual(smallestMult(5), 60);
-  - text: <code>smallestMult(7)</code> should return 420.
-    testString: assert.strictEqual(smallestMult(7), 420);
-  - text: <code>smallestMult(10)</code> should return 2520.
-    testString: assert.strictEqual(smallestMult(10), 2520);
-  - text: <code>smallestMult(13)</code> should return 360360.
-    testString: assert.strictEqual(smallestMult(13), 360360);
-  - text: <code>smallestMult(20)</code> should return 232792560.
-    testString: assert.strictEqual(smallestMult(20), 232792560);
+`smallestMult(5)` should return a number.
 
+```js
+assert(typeof smallestMult(5) === 'number');
 ```
 
-</section>
+`smallestMult(5)` should return 60.
 
-## Challenge Seed
-<section id='challengeSeed'>
+```js
+assert.strictEqual(smallestMult(5), 60);
+```
 
-<div id='js-seed'>
+`smallestMult(7)` should return 420.
+
+```js
+assert.strictEqual(smallestMult(7), 420);
+```
+
+`smallestMult(10)` should return 2520.
+
+```js
+assert.strictEqual(smallestMult(10), 2520);
+```
+
+`smallestMult(13)` should return 360360.
+
+```js
+assert.strictEqual(smallestMult(13), 360360);
+```
+
+`smallestMult(20)` should return 232792560.
+
+```js
+assert.strictEqual(smallestMult(20), 232792560);
+```
+
+# --seed--
+
+## --seed-contents--
 
 ```js
 function smallestMult(n) {
@@ -55,15 +62,7 @@ function smallestMult(n) {
 smallestMult(20);
 ```
 
-</div>
-
-
-
-</section>
-
-## Solution
-<section id='solution'>
-
+# --solutions--
 
 ```js
 function smallestMult(n){
@@ -81,5 +80,3 @@ function smallestMult(n){
   return result;
 }
 ```
-
-</section>