fix(editor): Ensure reliable unregistration of block variations

[firestar300]

Introduces a mechanism to wait for target blocks to be fully registered in the editor store before attempting to unregister their variations. This prevents potential issues where variations might not be unregistered if blocks are not yet available when domReady fires.

Additionally, this change refactors block style and variation unregistration into dedicated helper functions for improved code organization and readability.

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Note

Medium Risk
Changes Gutenberg editor initialization timing and settings global name, which could impact block style/variation availability in the editor if misconfigured.

Overview
Improves reliability of Gutenberg variation unregistration by waiting until target blocks are registered (via @wordpress/data subscribe + getBlockType) before calling unregisterBlockVariation.

Refactors editor-side unregistration into helper functions, makes disabled styles handling accept single or array values, and renames the injected settings global from BFFEditorSettings to BEAPI_EDITOR_SETTINGS (updated in both PHP inline script and src/js/editor.js).

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