Improve how assets are enqueued

[gigitux]

To fix #9331, we did a dirty patch to change how assets are enqueued on the Site Editor (#9332).

We have to revisit the entire process to be sure that the assets are enqueued in the right way and only when they are necessary.

To understand why this if/else statement exists you can reproduce the issues quickly by doing the following:

1. Replace the if/else statement with just add_action( 'enqueue_block_editor_assets', array( $this, 'register_data_script' ) );
2. Go to Pages > All Pages and see the console error: Payment gateway with handle 'wc-payment-method-cod' has been deactivated in Cart and Checkout blocks because its dependency 'wc-settings' is not registered. Read the docs about registering assets for payment methods: . This error fails the E2E tests
3. Now replace the if/else statement with just add_action( 'init', array( $this, 'register_data_script' ) );
4. Load the Single Product block template and see no assets loading.