feat: Add currency module and remove currency models from region and pricing modules (#6536)

What:
- Creates a new currency module
- Removes currency model from the pricing module
- Removes currency model from region module

integration-tests/plugins/__tests__/cart/store/cart.workflows.spec.ts

@@ -63,7 +63,7 @@ describe("Carts workflows", () => {
 
   beforeEach(async () => {
     await adminSeeder(dbConnection)
-    await regionModuleService.createDefaultCountriesAndCurrencies()
+    await regionModuleService.createDefaultCountries()
 
     // Here, so we don't have to create a region for each test
     defaultRegion = await regionModuleService.create({

integration-tests/plugins/__tests__/cart/store/carts.spec.ts

@@ -59,7 +59,7 @@ describe("Store Carts API", () => {
 
   beforeEach(async () => {
     await adminSeeder(dbConnection)
-    await regionModuleService.createDefaultCountriesAndCurrencies()
+    await regionModuleService.createDefaultCountries()
 
     // Here, so we don't have to create a region for each test
     defaultRegion = await regionModuleService.create({