use youtube-nocookie for embeds and add query params

[riknoll]

also adds the following safeguards:

• rel=0 removes related videos
• modestbranding=1 makes the youtube logo smaller
• autoplay=0 prevents autoplay
• showinfo=0 prevents youtube video info from showing up
• a sandbox attribute without allow-popups prevents kids from following any links inside the video frame

i found this page helpful: https://medium.com/@hakim.ziad/how-we-safely-embed-youtube-videos-in-educational-websites-c26e5a9817e5

upload target: https://arcade.makecode.com/app/831574c93f3d2096578d27258a796f9f8dbf459d-898c8b819f

[abchatra]

Awesome! Thank you!