`ReactiveTextField` doesn't dispose the `TextEditingController`

[remonke]

ReactiveTextField internally initializes a TextEditingController. However, it doesn't get disposed, which causes memory leaks.

Here's the relevant code from reactive_text_field.dart

class _ReactiveTextFieldState<T>
    extends ReactiveFocusableFormFieldState<T, String> {
  late TextEditingController _textController;

  @override
  void initState() {
    super.initState();
    _initializeTextController();
  }

  @override
  void onControlValueChanged(dynamic value) {
    final effectiveValue = (value == null) ? '' : value.toString();
    _textController.value = _textController.value.copyWith(
      text: effectiveValue,
      selection: TextSelection.collapsed(offset: effectiveValue.length),
      composing: TextRange.empty,
    );

    super.onControlValueChanged(value);
  }

  @override
  ControlValueAccessor<T, String> selectValueAccessor() {
    if (control is FormControl<int>) {
      return IntValueAccessor() as ControlValueAccessor<T, String>;
    } else if (control is FormControl<double>) {
      return DoubleValueAccessor() as ControlValueAccessor<T, String>;
    } else if (control is FormControl<DateTime>) {
      return DateTimeValueAccessor() as ControlValueAccessor<T, String>;
    } else if (control is FormControl<TimeOfDay>) {
      return TimeOfDayValueAccessor() as ControlValueAccessor<T, String>;
    }

    return super.selectValueAccessor();
  }

  void _initializeTextController() {
    final initialValue = value;
    final currentWidget = widget as ReactiveTextField<T>;
    _textController = (currentWidget._textController != null)
        ? currentWidget._textController!
        : TextEditingController();
    _textController.text = initialValue == null ? '' : initialValue.toString();
  }
}

[vicenterusso]

@joanpablo can you merge that simple fix?