Added placeholder + prefix icon for cupertino typeahead

Author: M-Ahal

packages/reactive_flutter_typeahead/lib/src/reactive_cupertino_typeahead.dart

@@ -112,6 +112,8 @@ class ReactiveCupertinoTypeAhead<T, V> extends ReactiveFormField<T, V> {
     SuggestionsController<V>? suggestionsController,
     BoxDecoration? decoration,
     EdgeInsetsGeometry padding = const EdgeInsets.all(6.0),
+    String? placeholder,
+    Widget? prefix,
     TextInputType? keyboardType,
     TextCapitalization textCapitalization = TextCapitalization.none,
     TextInputAction? textInputAction,
@@ -162,6 +164,8 @@ class ReactiveCupertinoTypeAhead<T, V> extends ReactiveFormField<T, V> {
                   enabled: enabled,
                   decoration: decoration,
                   padding: padding,
+                  placeholder: placeholder,
+                  prefix: prefix,
                   keyboardType: keyboardType,
                   textCapitalization: textCapitalization,
                   textInputAction: textInputAction,