Accessibility: Improve Focus Management and Markup of Edit Profile Photo Link and Modal

[mercime]

While tabbing through Users - Member > Extended Profile screen and pressing Enter on the "Edit Profile Photo" link (where we should add role="button"), the Modal shows up as it should. However, the focus should remain on the modal and elements within until the user presses the Spacebar on the "X" button to close the modal whereupon the focus should return to the "Edit Profile Photo" link/button. But this isn't the case for the current implementation.

I'm attaching an animated gif to show that the focus jumps from the modal to outside and behind the modal (browser toolbar then the WP admin menu etc) while it is open. This is very confusing for keyboard and users of assistive technologies.