A consistent aspect ratio component

[scruffian]

What problem does this address?

We have two copies of the image aspect ratios (one in Global Styles (and the Image block), and the other in the Featured Image block #47854).

What is your proposed solution?

We should find a way to share this code, potentially moving the width/height/scale/aspect ratios to components. These experiences should be consistent across the board, as well as future implementations (like the Cover block #54032).

This is blocked by #55059, which allows for the Image block to utilize units for image sizes. When that's complete, these controls can be 1:1 across both (and future) areas.

Other ideas

1. The default aspect ratios could be an editor setting (provided by Add aspect ratio presets support via theme.json #47271), that could be open to be overridden via global styles

[ajlende]

In #47271 the settings are saved in theme.json

[cbirdsong]

This would also be addressed by eliminating one-off blocks like this. See:

• Create a system for inserting site/post metadata into generic blocks #37753
• Bits: Dynamic replacement of server-provided content (tokens, "shortcodes 2.0") #39831

[richtabor]

@scruffian The idea here is that the aspect ratios will be part of Global Styles and referenced throughout related controls. This PR (#47271) was the start of that, but we held off for 6.2.

Is this what you're referring to?

[scruffian]

At the moment we have some settings in Global Styles and some in the Post Featured Image block. They are the same, but they are separate lists - so if we change one there's a risk we forget to change the other and they'll become out of sync. We should update this so that there is only one list to remove that risk.

[jasmussen]

Following up on this one, now that the Cover block has an aspect ratio control, it'd be good to bring that to Featured Image and Image as well, since it's the correct 40px size.

See also #58230