Blocks: Introduce filter to allow easy addition of hooked blocks

[Bernhard Reiter]

As a follow-up to [56649], it would be good to introduce a filter that allows even easier conditional addition (or removal) of hooked blocks for a given anchor block and relative position.

Something along the following lines:

<?php
function insert_shopping_cart_hooked_block( $hooked_blocks, $position, $anchor_block, $context ) {
        if ( 'after' === $position && 'core/navigation' && $anchor_block && /** $context is header template part **/ ) {
                $hooked_blocks[] = 'mycommerce/shopping-cart';
        }
        return $hooked_blocks;
}
add_filter( 'hooked_block_types', 'insert_shopping_cart_hooked_block', 10, 4 );