a11y: Video widget accessibility

[ramiy]

Description

The video widget need some accessibility love!

1. Name - The iframe should have an accessibility name (https://fae.disability.illinois.edu/rulesets/FRAME_2/), either title or aria-label tags.

2. Action - The play icon should have some text saying "Play video" or some thing like that. Currently, regular visitors see the play button and understand that clicking the icon actives the video, but blind people don't see the icon. We need to add an assistive text for them.

3. Markup - The play icon wrapper is a <div>, it should be a <button>. The second approach is to add role="button" to the <div> tag.

[ashybaye]

@ramiy
Hello! Trying to make sure that the video components are indeed passing the accessibility checks. Was the title attribute added to the iframes? I still can't see it in the code when adding videos. Thank you!