检查当前区块类型是否支持所请求的边界特征。

如果`__experimentalBorder`支持标志是一个布尔值`true`，那么所有的边界支持功能都是可用的。否则，嵌套在`experimentalBorder`下的特定特征支持标志必须被启用，才能选择该特征。

function wp_has_border_feature_support( $block_type, $feature, $default_value = false ) {
	// Check if all border support features have been opted into via `"__experimentalBorder": true`.
	if (
		property_exists( $block_type, 'supports' ) &&
		( true === _wp_array_get( $block_type->supports, array( '__experimentalBorder' ), $default_value ) )
	) {
		return true;
	}

	// Check if the specific feature has been opted into individually
	// via nested flag under `__experimentalBorder`.
	return block_has_support( $block_type, array( '__experimentalBorder', $feature ), $default_value );
}