Checks whether it is possible to serialize a `GBoxed` of type `gboxed_type` into a [struct@Json.
Node].
The type of the node is placed inside `node_type` if the function returns `TRUE`, and it's undefined otherwise.
| gboxed_type |
a boxed type |
| node_type |
the node type to which the boxed type can be serialized into |
|
`TRUE` if the type can be serialized, and `FALSE` otherwise |