feat: add OTPInput component

[Jasleen-Kaur96]

Description

Adds a new OTPInput component to react-native-paper for handling one-time password (OTP) inputs in a structured and accessible way.

Features

• Configurable input length (default: 6)
• Controlled component API (value, onChangeText)
• Automatically focuses next input on entry
• Handles backspace navigation (clears and moves to previous input)
• Supports paste and full-code autofill (iOS SMS OTP, Android autofill)
• Calls onComplete when all digits are filled
• Accessible with proper labels for each input

Includes

• Example screen (OTPInputExample)
• Documentation (otp-input.md)
• Unit tests covering input, paste, and completion behavior

Motivation

OTP inputs are a common requirement in authentication flows, but currently require custom implementations when using react-native-paper.

This component provides:

• A consistent UX aligned with Material Design
• Built-in handling for tricky behaviors (focus management, paste, autofill)
• A reusable and tested solution within the library

Implementation Notes

• Built on top of existing TextInput to ensure theme consistency
• Uses internal theming (useInternalTheme) for proper styling
• Designed as a controlled component for predictable state management

Related Issue

Closes #4860

[callstack-bot]

Hey @Jasleen-Kaur96, thank you for your pull request 🤗. The documentation from this branch can be viewed here.