Currency setting (#7390)

* Add new global setting for currency options

- Moving away from external configuration
- Refactor currency support code into new file

* Refactoring

- Move functions into currency.py

* Limit choices for default currency

* Improve validation

* Adds data migration for existing currency selection

* Docs updates

* Remove currency config from external settings

* bump api version

* Add debug message

* Add unit tests

* Fix after_change_currency func

* Fix after_change_currency func

* Revert change to after_chance_currency

* Revert other change

src/frontend/src/pages/Index/Settings/SystemSettings.tsx

@@ -109,6 +109,7 @@ export default function SystemSettings() {
             <GlobalSettingList
               keys={[
                 'INVENTREE_DEFAULT_CURRENCY',
+                'CURRENCY_CODES',
                 'PART_INTERNAL_PRICE',
                 'PART_BOM_USE_INTERNAL_PRICE',
                 'PRICING_DECIMAL_PLACES_MIN',