improved image `sizes` for left/right/center alignment

[mukeshpanchal27]

Overview

Follow-up: #1187
This issue cover calculate sizes for left/right/center alignment.

Approach

For initial work:

• Only return a smaller image size if the content or wide size is larger than the image size.
  • If content size is 620px and content use thumbnail the the size will use thumbnail 150px image size instead of 620px.
• Parse the width value for "px"; for other types( vw, min() ), return the image width according to the default WordPress behaviour.

Core editor issues:

• The image markup is missing default width and height attributes. These attributes are set when the image is resized.
• The Cover block does not add the image width attribute.
  • When adding a new Cover block, it defaults to using the full image size.
  • When adding an Image block, selecting a thumbnail, and transforming it to a Cover block, the thumbnail image is used instead of the full image. There should be an image size attribute in the Cover block to display this information.

[joemcgill]

@mukeshpanchal27 once #1251 is fixed, I think this issue should be updated to focus only on applying a maximum constraint to left/right/center aligned images that are larger than their container.

I'm also unclear about what you mean by:

Parse the width value for "px"; for other types( vw, min() ), return the image width according to the default WordPress behaviour.

Could you clarify?

[ramiy]

Any chance to support start/end for RTL websites?

[joemcgill]

This is now unblocked since #1251 is fixed.