Some special characters like '\v' are encoded using 6 characters, which
currently does not work because the VLA size asumes a maximum of 4 characters
per encoded special character. This patch refactors this logic to avoid using
VLAs at all and encodes the string directly into the builder.
See #471
Similar to wp_spa_json_builder_add_property(), we need to make sure the dst
array in wp_spa_json_builder_add_string() has room for the null character
because builder_add() expects it.
Fixes#471
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.
The spa-json parser allows some interesting things to happen, which
are not valid JSON, but we use them for readability in config files...
- The separator may be = or just a space instead of :
- Strings may be unquoted
- Commas may be omitted
