Json Flattening

[TheNitesWhoSay]

RareJson should support opt-in (with annotations) flattening of super classes and nested objects.

e.g.

struct Parent { int a; ... }
struct Child : Parent { int b; ... }

Which today when writing child would come out something like...

{
  "b": 12345,
  "parent": {
    "a": 12345
  }
}

Should be possible to instead have written like...

{
  "a": 12345,
  "b": 12345
}

Some of the challenges identified earlier were as follows:

1.) Flattening should potentially apply recursively, pulling the hierarchy of ancestor classes into sub-classes if directed to do so
2.) Data-hiding and naming collisions need to be accounted for
3.) Open questions of whose field clusters unknown fields belong to
4.) There's no reason flattening couldn't also apply to regular fields of certain types, such as nested reflected objects
5.) There's a huge amount of logic changes related to pretty print and affixing that this would necessitate - you can no longer rely on analysis of the current object to tell if something is the first field

[TheNitesWhoSay]

Some earlier thoughts on what some of this might look like: https://godbolt.org/z/4GYnPz