The previous naming convention was confusing because it did not make
it explicit that the string is not being copied. We had this wrong already
in the Lua bindings and thanks to some miracle it hasn't backfired so far
(it was using the "wrap" behaviour with a string that doesn't stay alive).
In some places we actually need the "copy" behaviour and in some other
places we need the "wrap" behaviour, so let's have both variants available.
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.
