Add Orange Money API Adapter

[Einswilli]

Description:

Integrate Orange Money's mobile payment system covering 17 African countries into EasySwitch.

Key Requirements:

• Handle country-specific API endpoints (.sn, .ci, etc.)
• Implement auth with X-AUTH-TOKEN header
• Support bulk payments endpoint
• Webhook signature validation

# Target usage example:
await client.send_payment(
    provider="orange",
    amount=5000,
    phone_number="22507081234",  # Côte d'Ivoire format
    currency="XOF",
    merchant_code="MERCH123"
)