This allows partially parsing a json object, allowing some parts to be
passed on as strings to another component that does its own parsing
(ex. a pipewire module)
Since the string length returned by wp_spa_pod_get_data() does not always match
the size of the actual json object because it is stored in contiguous memory, we
cannot always rely on that API to get the json string data.
The new wp_spa_pod_to_string() always allocates a new string with the same
length as the json size, guaranteeing that the string returned always represents
the json object, regardless of whether it is nested or not. It is always
recommented to use wp_spa_pod_to_string() unless you know what you are doing.
