refactor: reduce code duplication across OCPP services, UI server, and configuration

refactor: reduce code duplication across OCPP services, UI server, and configuration

- Centralize AJV instantiation into createAjv() factory in OCPPServiceUtils
- Centralize payload validator config creation into createPayloadConfigs() generic
  factory, simplifying OCPP16/20ServiceUtils from multi-line .map() to one-liners
- Move rate limiter creation from module-level duplicates in UIHttpServer and
  UIMCPServer to a shared instance property on AbstractUIServer
- Extract 200-line checkDeprecatedConfigurationKeys() and helpers from
  Configuration.ts into dedicated ConfigurationMigration.ts module