* Move type defs
* Move type guards
* Fix imports
* Extract prepareTotalItems to TS file
* usePaymentMethodInterface as TS file
* Fix TS props
* Fix currency type defs
* Add return type to usePaymentMethodInterface
* Add key prop to CartTotalItem
* Fixed up js tests
* Move SymbolPosition into type-defs package
Co-authored-by: Thomas Roberts <thomas.roberts@automattic.com>
Mike Jolley