feat: add html element extractor

[a2937]

Checklist:

• I have read freeCodeCamp's contribution guidelines.
• My pull request has a descriptive title (not a vague title like Update index.md)

Closes #XXXXX

A variation of this particular regex was used in PRs like freeCodeCamp/freeCodeCamp#55547. I expect this kind of thing to come up a little bit more often in the future which is why I'm adding it to your curriculum helpers. I've also generalized this in an attempt to increase the usefulness. Though without that extra parameter present it will just extract head elements.

[ShaunSHamilton]

We can definitely add this, but I disagree with this expectation:

I expect this kind of thing to come up a little bit more often in the future which is why I'm adding it to your curriculum helpers.

Ideally, Regex should NOT be used at all for the tests. In that one case, it is forcibly used, because the browser changes the html in the preview.

[a2937]

Yeah ideally it shouldn't.

[a2937]

I also hopefully will find a way to convert this from Regex into something that uses string manipulation methods.

[ojeytonwilliams]

Hey @a2937 @ShaunSHamilton is this still something we want? Shaun, I know you had concerns.

[a2937]

I can update the description and make the merge changes if this is something that seems useful.

[ShaunSHamilton]

I think this can be useful. We just need the suggested changes and conflicts.

[ShaunSHamilton]

This would be confusing if we forget it defaults to head - there is no logical reason to default.