200 OK is returned only if all validations pass and the OTP is dispatched successfully.curl --location --request POST '/onboarding/start' \
--header 'Content-Type: application/json' \
--data-raw '{
"mobile_number": "966501234567",
"national_id": "1234567890",
"locale": "ar",
"external_reference": "partner-ref-abc123"
}'{
"session_id": "1ffd059c-17ea-40a8-8aef-70fd0307db82"
}