Add CSS classes for block spacing to the incoming attributes array.

This will be applied to the block markup in the front-end.

function wp_apply_spacing_support( $block_type, $block_attributes ) {
	if ( wp_should_skip_block_supports_serialization( $block_type, 'spacing' ) ) {
		return array();
	}

	$attributes          = array();
	$has_padding_support = block_has_support( $block_type, array( 'spacing', 'padding' ), false );
	$has_margin_support  = block_has_support( $block_type, array( 'spacing', 'margin' ), false );
	$block_styles        = isset( $block_attributes['style'] ) ? $block_attributes['style'] : null;

	if ( ! $block_styles ) {
		return $attributes;
	}

	$skip_padding                    = wp_should_skip_block_supports_serialization( $block_type, 'spacing', 'padding' );
	$skip_margin                     = wp_should_skip_block_supports_serialization( $block_type, 'spacing', 'margin' );
	$spacing_block_styles            = array();
	$spacing_block_styles['padding'] = $has_padding_support && ! $skip_padding ? _wp_array_get( $block_styles, array( 'spacing', 'padding' ), null ) : null;
	$spacing_block_styles['margin']  = $has_margin_support && ! $skip_margin ? _wp_array_get( $block_styles, array( 'spacing', 'margin' ), null ) : null;
	$styles                          = wp_style_engine_get_styles( array( 'spacing' => $spacing_block_styles ) );

	if ( ! empty( $styles['css'] ) ) {
		$attributes['style'] = $styles['css'];
	}

	return $attributes;
}