Epic - Migrate to WordPress Core block API V3

[AmnestyAM]

Sprints allocated

Number of sprints: one
Link to sprint if known: TBC

https://developer.wordpress.org/block-editor/reference-guides/block-api/

Goals

• Less code to manage
• Faster CMS
• Better HTTP2 support

Process

1. Scaffold new block directory structure and build process #441
2. Migrate custom blocks to current best-practice format #442
3. Update build targets #443

To be backported

• Bug - AR meta box is missing margin  #478
• Bug - AR Menu goes off the page if a menu it with a child at the end of the menu #480
• Bug - Links are not underlined in the CMS editor  #508
• Bug - featured image - show caption feature not working #517
• Bug - resource download block - drop down text unreadable when in section with white text #562
• Bug - responsive iframe block - caption not working with formatted text #563
• https://github.com/amnestywebsite/amnesty-wp-theme/issues/2751 (done)

[AmnestyAM]

not these blocks as we are removing them #291