Add support generate PropertyAccessor(getter, setter)

[ivk1800]

I not found how generate property and getter for class.

examples:

DateTime get now => DateTime.now();

DateTime get now {
    return DateTime.now();
}

DateTime _now = DateTime.now();
set now(DateTime date) => _now = date;

set now(DateTime date) {
    _now = date;
}

[stonega]

void _generateMethod(MethodBuilder b) {
    b
      ..returns = datetime
      ..type = MethodType.getter
      ..name = 'now'
      ..body = Code(""" 
      return DateTime.now();
      """);
  }

This is supported by set method type.

[ivk1800]

not enough full documentation for api.