feat: date picker startOnYearSelection

[Tatsunori-Morita]

Summary

This pull request addresses issue #67 by adding a feature that allows the year picker to be shown first.

Implementation details:

• For DatePickerDialog: Used an OnShowListener so that when the dialog is displayed, the year view button is retrieved via the date_picker_header_year ID and programmatically clicked to show the year selector.
• For MaterialDatePicker: Retrieved the view responsible for displaying the year within the picker’s view group and programmatically triggered it to switch to the year selection view.

Test Plan

Tested using an Android emulator.

• Pixel 6 (Android 12) DatePickerDialog

https://github.com/user-attachments/assets/3f7dc078-9798-4ea5-9c41-0ae67defae82

• Pixel 6 (Android 12) MaterialDatePicker

https://github.com/user-attachments/assets/e71162b5-83ac-48cd-9a01-5d993b3389bd

• Pixel 7 (Android 14) DatePickerDialog

https://github.com/user-attachments/assets/510a7b30-4fc8-401c-ab71-d27ef8de60c9

• Pixel 7 (Android 14) MaterialDatePicker

https://github.com/user-attachments/assets/a0fd76e5-b606-405c-a0b5-c997a0017047

• Nexus 5X (Android 7) DatePickerDialog

https://github.com/user-attachments/assets/c1c63264-d1f1-4927-b507-ec1db23b3676

• Nexus 5X (Android 7) MaterialDatePicker

https://github.com/user-attachments/assets/236f5c58-38fe-4142-b168-47484482e5a1

What's required for testing (prerequisites)?

What are the steps to reproduce (after prerequisites)?

Compatibility

OS	Implemented
iOS	❌
Android	✅

Checklist

• [x] I have tested this on a device and a simulator
• [x] I added the documentation in README.md
• [x] I updated the typed files (TS and Flow)
• [x] I added a sample use of the API in the example project (example/App.js)
• [ ] I have added automated tests, either in JS or e2e tests, as applicable