feat: Add functionality to delete all discovered contacts

- Implemented a new method to remove all discovered contacts from the list.
- Added confirmation dialog for deleting all discovered contacts in the discovery screen.
- Updated localization files to include new strings for deleting all discovered contacts.
- Refactored contact import logic to streamline the process.
- Enhanced the discovery handling to notify users appropriately based on settings.

lib/screens/contacts_screen.dart

@@ -222,7 +222,7 @@ class _ContactsScreenState extends State<ContactsScreen>
       final bytes = hex2Uint8List(hexString);
       final importContactFrame = buildImportContactFrame(bytes);
       _pendingOperations.add(ContactOperationType.import);
-      await connector.sendFrame(importContactFrame, expectsGenericAck: true);
+      connector.importContact(importContactFrame);
     } catch (e) {
       if (mounted) {
         ScaffoldMessenger.of(context).showSnackBar(