Update OpenID Connect URLs to match docs
- URLs were updated. See https://developer.paypal.com/docs/api/auth-headers/#obtain-users-consent
- Using `php-cs-fixer` tool.
- Updated OpenId classes to be in API namespace - Updated PP Naming Convention to PayPal Naming Convention - FormatConverter Class got its own namespace - Handlers are grouped in Handler namespace - Samples and Tests Updated Accordingly
