Gallery block: Add images size selector

[mmtr]

Description

Add an image size selector to the gallery block that allows users to choose the size of the images. It defaults to the large size.

Fixes #1450

How has this been tested?

Manually, following the steps below:

• Insert a gallery block and add some images.
• Verify there is a new images size selector that defaults to "Large".
• Choose a different size.
• Verify the editor loads the images in the selected size.
• Publish the post and verify the frontend loads the images in the selected size.
• Open an existing post containing a gallery block and verify images in large size are still loaded.

Screenshots

Types of changes

Enhancement.

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.
• I've updated all React Native files affected by any refactorings/renamings in this PR. .

[jorgefilipecosta]

Hi @mmtr, thank you for this PR. It worked great on my tests. I just left a comment related to the number of network requests we could be making.

[idea--list]

Applied these changes on my localhost, seems to pass my manual tests.
This is an awesome PR, fixes a long standing severe issue with GB.
(Also cover and media&text blocks would need this setting)

[jorgefilipecosta]

Worked well on my tests 👍

[ShareTextures]

@mmtr I installed Gutenberg 7.2 but I can't see image size selector?

[mmtr]

@mmtr I installed Gutenberg 7.2 but I can't see image size selector?

It only shows up when the gallery block contains an image coming from the media library. If the gallery block is empty or contains only images that are just URLs, the selector won't cause any effect and thus is hidden.

Can you verify you are not using the gallery block under one of these scenarios?

[ShareTextures]

@mmtr I installed Gutenberg 7.2 but I can't see image size selector?

It only shows up when the gallery block contains an image coming from the media library. If the gallery block is empty or contains only images that are just URLs, the selector won't cause any effect and thus is hidden.

Can you verify you are not using the gallery block under one of these scenarios?

It's interesting I tried it another computer and it's show it now. Cookies possible :) Thanks

Edit: It setup as a thumbnail but at the single-post page, it still serving image full size instead of thumbnail. Link

[mmtr]

Let's move the discussion to #19556