Backport the new json_from_string() function
JSON-GLib 1.2.0 introduced a new function called json_from_string()
.
It is an handy function that allows us to obtain a jsonNode with just a single operation.
This function had to be backported, and modified a little, because we are
targeting Scout that has an older JSON-GLib version that misses both
json_from_string()
and json_parser_steal_root()
(that was used in
json_from_string()
).
/cc @smcv