JSON serializer which serializes nil-Arrays as `[]` and nil-maps als `{}`.

Idea from: https://github.com/homelight/json

Forked from https://github.com/golang/go/tree/547e8e22fe565d65d1fd4d6e71436a5a855447b0/src/encoding/json ( tag go1.20.2 )

Added:

 - `MarshalSafeCollections()` method
 - `Encoder.nilSafeSlices` and `Encoder.nilSafeMaps` fields