Incorrect codegen behaviour with nested structure and non-string values inside parameter map

[solonovamax]

If you use a nested structure within the parameter map, it will generate invalid code.

Example:

example:
  keys:
    type: string_array

  __map_keys:
    string_value:
      type: string
    
    bool_value:
      type: bool

    nested:
      foo:
        type: int
      bar:
        type: string
      baz:
        type: bool

this will cause it to generate code like:

StackParams get_stack_params() {
  Params params = get_params();
  StackParams output;
  output.__map_keys.nested.foo = params.__map_keys.nested.foo;
  output.__map_keys.nested.baz = params.__map_keys.nested.baz;

  return output;
}

notice how it doesn't have the bar parameter, but it does have the foo and baz parameters.