Field Values that are Ecto Embedded Structs or Embedded Lists

[jeregrine]

Right now we don't explicitly support Ecto Embedded schemas, if you manually do functions you can strip away the Struct meta data and embed the raw map.

JSON API does allow for any json type including lists or objects.

Since these embedded data structures typically don't have IDs and are not typically query-able as resources they should not be included as relationships.

We could make this easier by recognizing that the field is a struct and pulling out non-struct fields with Map.from_struct and structs from lists.