JSON Serialization: Consistent indentation

[ChristianGruen]

json elements should be indented the same way as maps:

for $json in (
  <json type="object"><A/></json>,
  { 'A': '' }
)
return serialize($json, { 'method': 'json', 'indent': true() })

{
  "A":""
}
{
  "A": ""
}