Refactor ForexRateApiService to remove API key dependency and update README and launch configurations

Signed-off-by: Hans Kokx <hans.d.kokx@gmail.com>

test/backup_restore_compatibility_test.dart

@@ -31,18 +31,18 @@ class _FakeStorageService extends StorageService {
   }
 }
 
-class _FakeExchangeService extends ForexRateApiService {
+class _FakeExchangeService extends FrankfurterApiService {
   _FakeExchangeService({required this.quote})
     : super(httpClient: http.Client(), apiKey: 'test-key');
 
   final double quote;
 
   @override
-  Future<ForexConversionResult> convertUsdToSek({
+  Future<ConversionResult> convertUsdToSek({
     required DateTime estDate,
     required double amount,
   }) async {
-    return ForexConversionResult(quote: quote, result: quote * amount);
+    return ConversionResult(quote: quote, result: quote * amount);
   }
 }
 

test/notification_scheduling_test.dart

@@ -29,15 +29,15 @@ class _FakeStorageService extends StorageService {
   }
 }
 
-class _FakeExchangeService extends ForexRateApiService {
+class _FakeExchangeService extends FrankfurterApiService {
   _FakeExchangeService() : super(httpClient: http.Client(), apiKey: 'test-key');
 
   @override
-  Future<ForexConversionResult> convertUsdToSek({
+  Future<ConversionResult> convertUsdToSek({
     required DateTime estDate,
     required double amount,
   }) async {
-    return ForexConversionResult(quote: 10, result: amount * 10);
+    return ConversionResult(quote: 10, result: amount * 10);
   }
 }