Video block: Add support for aspect ratio control

[jasmussen]

The video block does not offer much in the way of dimension tools:

Allowing you to pick an aspect ratio would allow you to more easily combine different poster images of a different size and shape than the video itself, and still allow both to function. This use case came up as part of working on #65776.

To test, this CSS would do the trick:

video {
    aspect-ratio: 1/1;
}

[youknowriad]

This seems like a duplicate of #60911

[up1512001]

@jasmussen raised PR for this, can you please review 🙇‍♂
#66946

[Mamaduka]

Closing this as a duplicate of #60911.

[jasmussen]

Thanks folks for the cleanup! 🙏