PHP backports for WP 6.8

[Mamaduka]

• Add support for positioning child blocks inside a Grid block. wordpress-develop#6910
  • Add Column Start and Row Start controls to Grid children #59483
  • Add a Row control to grid layout in manual mode. #60652
  • Try using manualPlacement attribute to set manual grid mode and allow responsive behaviour in both modes. #62777
  • Try inserting blocks directly in empty grid cells #63108
  • Fix responsive behaviour so both column start and column span are taken into account #63464
• Feature: Set editor rendering mode by post type wordpress-develop#7129
  • Feature: Set editor rendering mode by post type #62304
  • Plugin: Fix eligibility check for post types' default rendering mode #67879
• Fix wav file not getting uploaded in Gutenberg  wordpress-develop#7265
  • Media: add x-wav mime type for wav files in Firefox #66850
  • Media: check for wav mime type using isset  #66947
• Theme JSON: remove redundant check and relocate $selectors assignment wordpress-develop#7575
  • Theme JSON: remove redundant check and relocate $selectors assignment #66154
• Block editor: remove reusable blocks and pattern UI stylesheets from iframe wordpress-develop#7604
  • Block editor: remove reusable blocks stylesheet from iframe #66285
  • Clean up: adjust reusable-blocks dependencies #66302
  • Block editor: remove patterns UI stylesheet from iframe #66306
• Site Editor: remove content styles outside canvas wordpress-develop#7643
  • Site Editor: remove content styles outside canvas #66432
  • Site Editor: restore block-library editor.css outside canvas #66556
• Global styles: preload user global styles based on user caps wordpress-develop#7681
  • Global styles: preload user global styles based on user caps #66541
• Site editor: preload settings wordpress-develop#7687
  • Site Editor: preload settings requests #66488
  • Preload: fix e2e test #67497
• Site editor: preload post and template lookups if needed wordpress-develop#7695
  • Site editor: preload post if needed #66631
  • Preload: parse post ID from p (path) #67465
  • Site Editor: speed up load by preloading home and front-page templates #66579
  • Site Editor: Pages: Preload template lookup #66654
  • [mini] Preload: add post type #67518
• Theme JSON: replace top-level background style objects on merge wordpress-develop#7697
  • Theme JSON: replace top-level background style objects on merge #66656
• Theme JSON Resolver: remove theme json merge in resolve_theme_file_uris wordpress-develop#7698
  • Theme JSON Resolver: remove theme json merge in resolve_theme_file_uris #66662
• Section Styles: Fix removal of insecure properties for block style variations wordpress-develop#7759
  • Section Styles: Fix insecure properties removal for inner block types and elements #66896
• Theme JSON: include block style variations in path only output of get_block_nodes wordpress-develop#7784
  • Theme JSON: include block style variations in path only output of get_block_nodes #66948
• Theme.json: Fix complex variation selectors when using selectors API wordpress-develop#7825
  • Block Style Variations: Fix complex variation selectors when using selectors API #67061
• REST API: Terms: Respect taxonomy's default query args wordpress-develop#7848
  • Terms: Respect order specified by register_taxonomy() #67154
• Add stylebook path to exceptions for classic themes in site editor. wordpress-develop#7865
  • Add stylebook screen for classic themes #66851
  • Stylebook: add the Appearance -> Design submenu through admin_menu action #68174
• Add default_template_part_areas and default_template_types to site index endpoint wordpress-develop#7895
  • Move default template types and template part areas to REST API #66459
• Block Hooks: Apply to Post Content (on frontend and in editor) wordpress-develop#7898
  • Block Hooks: Apply to Post Content (on frontend and in editor) #67272
• Site Editor: Redirect old urls to the new path based ones wordpress-develop#7903
  • Site Editor: Use path based routing instead of query args and site-editor.php routes #67199
  • Fast follow: Redirections of deprecated site editor URLs. #68971
• REST API: Add support for search_columns argument to the REST API wordpress-develop#7909
  • REST API: Support search_columns argument in the user endpoint #67330
• Update docblocks for wp_get_global_stylesheet and WP_Theme_JSON::get_stylesheet. wordpress-develop#7976
  • Update global stylesheet docblocks with custom-css parameter. #67716
• Add logic to sort posts by hierarchy wordpress-develop#8014
  • Proof of concept: visualize hierarchical data #66479
• Block Hooks: Apply to synced patterns wordpress-develop#8015
  • Synced Patterns: Apply Block Hooks #68058
• Fix/translatable strings in theme json wordpress-develop#8031
  • Make strings in theme.json translatable #66675
  • Add duotone and dimensions to the block level for translation #68243
• Changed Document Order wordpress-develop#8032
  • Updated @since Doc Order in Inline documentation #68003
• Editor: Set new default rendering mode for Pages wordpress-develop#8123
  • Editor: New default rendering mode for editor via post type supports #68549
  • Editor: Update post-type support key for new default rendering mode #68745
• Block Hooks: Add apply_block_hooks_to_content_from_post_object wordpress-develop#8212
  • Block Hooks: Fix truncation of post content #68926

[Mamaduka]

I just noticed that PRs related to Block Comments are marked for backporting. The feature is still experimental, and these PRs aren't blockers for WP 6.8.

I will move the PHP core for experimental features into the correct directory.

PR in question:

• made changes for comment rest api to support with block commenting wordpress-develop#7488 - seems a general improvement for Comments API.
• allow custom comment type to fetch avatar urls in comment api wordpress-develop#7498

cc @peterwilsoncc