Introduce `woocommerce_thankyou_order_received_text` filter

It is sometimes desirable to change the thank you text that appears on the thank you page without modifying/overriding the thankyou.php template file.

An example use case would be a plugin, that does not touch the templates, but may need to display a different message based on whatever information is available at that time (order status, payment method, etc).

For example - one may want to display a different message based on the order status. If it's on-hold, display "Your order has been received and is now on-hold". If it's processing, display "Your order has been received and is now being processed" - etc..