Description

This PR is best reviewed without whitespace changes.

Currently, drag and drop is controlled by a provider that keeps track of all the drop zone, checks to see which one is being dragged over and updates state for that drop zone with position info.

This seems all rather complex (and a source of many headaches) and I see no good reason for each drop zone to not manage its own state and events properly.

I've also removed storing position coordinates to state and instead using a callback to signal the position to the drop zone implementor, which can set its own state based on the coordinates. This way, we don't need to continuously set state for position changes but only for data derived from it.

Before	After

How has this been tested?

Test drag and drop of blocks in the editor, inner blocks, and placeholders.

Screenshots

Types of changes

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• I've tested my changes with keyboard and screen readers.
• 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 (please manually search all *.native.js files for terms that need renaming or removal).