[FR] React Native Authenticator: Add Dial Code Select

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- [X] I have [searched for duplicate or closed issues](https://github.com/aws-amplify/amplify-ui/issues?q=is%3Aissue+) and [discussions](https://github.com/aws-amplify/amplify-ui/discussions).
- [X] I have tried disabling all browser extensions or using a different browser
- [X] I have tried deleting the node_modules folder and reinstalling my dependencies
- [X] I have read the guide for [submitting bug reports](https://github.com/aws-amplify/amplify-ui/blob/main/CONTRIBUTING.md#bug-reports).

### On which framework/platform are you having an issue?

React Native

### Which UI component?

Authenticator

### How is your app built?

N/A

### What browsers are you seeing the problem on?

Chrome

### Please describe your bug.

It's not clear that what the correct phone number format is due to missing dial code select dropdown.


### What's the expected behaviour?

Should have a dial code select dropdown like on Web:

### Code Snippet

```typescript
// Put your code below this line.

```

### Additional information and screenshots

_No response_

Start at the React Native Authenticator phone-number input and compare it with the web Authenticator dial-code select shown in the issue. Confirm the expected phone-number format and the sign-up flow affected; done means users can choose a dial code and the resulting format is clear.

Written by the indexing model from the issue text.