fix: 1476-Video sound keeps playing after closing the popup it's in

[AbdelrahmanDeghedy]

Description

• This is a fix to this issue: https://github.com/ocadotechnology/rapid-router/issues/1476
• Added a function that stops the iframe video, and I called it on the play, and close modal buttons.

  How Has This Been Tested?

  stopVideoAfterPopup.webm

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This change is 

[AbdelrahmanDeghedy]

Reviewed 1 of 1 files at r1, all commit messages. Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @AbdelrahmanDeghedy)

game/static/game/js/drawing.js line 1020 at r1 (raw file):

  // https://gist.github.com/cferdinandi/9044694
  const video = document.getElementsByClassName("video");
  var iframeSrc = video[0].src;

Can you replace var with let please 🙏 😊

I have replaced it with a const since it's not mutated.