Iteration of the Block bindings API tracking issue.

This is what we expect to include in WordPress 6.6. We'll use this issue to share regular updates and progress.

• Bindings creation

Even though we'll probably won't add a UI to create bindings yet, we'd like to start discussing how it should work.

• Server APIs

• Improve the existing code
  • Block bindings: Remove not needed breaks in gutenberg_block_bindings_replace_html #61660
  • Block Bindings: Simplify the HTML replacement logic until the HTML API is ready #61236
• Revisit how sources access the needed context.
  • Add context needed by block bindings sources during its processing

• Editor APIs

• Improve the existing hook implementation.
  • Block bindings: don't use hooks #60724
• Add support for allowing editing.
  • Block bindings: don't use hooks #60724
• Simplify the HTML replacement logic until the HTML API is ready.
• Add callback so sources can decide when to lock/allow editing.
• Improve the UX when the editing of bound blocks is locked.
  • Add bindings panel in the block inspector controls: Once/if this is merged, we can revisit the existing toolbar indicators.
  • Filter pattern overrides source in bindings panel
  • Notify on save when users edit the value of a connected custom field instead of the post content.
  • Add indicator that an attribute is connected instead of hiding the controls.
• Define and implement UX for editing custom fields directly from blocks connected.
• Define how to work with placeholders.
• Revisit how sources access the needed context.
  • Block Bindings: rely on broader context instead of requiring direct block context #60826

• Core sources

• Use block bindings editor API to update pattern overrides.
  • Pattern overrides: use block binding editing API #60721
• Support editing in "Post meta" source.
  • Block Bindings: Allow editing in post meta source #61753

Beta phase fixes

• Fix site editor breaking when user selects bound and non-bound blocks at the same time.
• Fix applying bindings or pattern overrides to button blocks with empty text.
• Revert changes to replacement logic to prevent reported bugs: Gutenberg & Core.
• Change bindings panel title and add description.
• Fix showing double icons for connected blocks.
• Pattern Overrides: Prevent normal attribute updates when a __default binding exists.
• Remove connections icon and fix padding.
• Add e2e test to ensure block bindings work well with symbols and numbers.
• Only run block bindings Gutenberg logic for sites using WordPress versions below 6.5.
• Use preview instead of publishing post in block bindings tests.
• Pattern overrides: disallow override for image with caption/href.
• Pattern Overrides: Unable to set some attributes like Image block Aspect Ratio when editing the original pattern
• Ensure custom field changes work fine with revisions.