Add unit support for image block height and width

[richtabor]

In an effort to consolidate aspect ratio across blocks, let's add the unit control functionality that the Featured Image block supports for height and width, to the Image block. Note that aspect ratio should be maintained, regardless of units.

The image block only supports px currently:

As seen in the featured image block:

[bgardner]

@richtabor For consistency sake, should we mirror the order of Height / Width across the two blocks? Image is Width / Height while Featured Image is Height / Width. (If so, my vote is for the former)

[richtabor]

@richtabor For consistency sake, should we mirror the order of Height / Width across the two blocks? Image is Width / Height while Featured Image is Height / Width. (If so, my vote is for the former)

Certainly. I have this issue to consolidate into a proper component, which would make these 1:1 across the board. #47962

[gsallman]

Please, this needs to be implemented as soon as possible since the current implementation is proving to be a backward compatibility nightmare. The previous functionality used %-ages, which scaled responsively. The new implementation does not scale responsively, and if you open an old post to make a minor edit, any images in the post using the old % sizes are updated and given absolute sizes, which do not scale responsively. :(

In short, by using absolute scaling units (px), adding images to a post, adjusting their sizes, and having them responsively scale on various devices is impossible.

[brettsmason]

I'd love to see this implemented too. Having recently discovered its not possible to extend the list of build-in aspect ratios (unless anyone can could explain how?), this would be the next best thing. Or a way to enter a custom aspect ratio.