Add notification permission flow in settings

test/features/reminders/scheduling/reminder_scheduler_local_notifications_test.dart

@@ -59,12 +59,29 @@ void main() {
     expect(driver.initializeCalls, 1);
     expect(driver.cancelAllCalls, 1);
   });
+
+  test('requestPermissions delegates to notifications driver', () async {
+    final FakeReminderNotificationsDriver driver =
+        FakeReminderNotificationsDriver(permissionResult: true);
+    final LocalNotificationsReminderScheduler scheduler =
+        LocalNotificationsReminderScheduler(driver: driver);
+
+    final bool granted = await scheduler.requestPermissions();
+
+    expect(granted, isTrue);
+    expect(driver.initializeCalls, 1);
+    expect(driver.permissionRequests, 1);
+  });
 }
 
 class FakeReminderNotificationsDriver implements ReminderNotificationsDriver {
+  FakeReminderNotificationsDriver({this.permissionResult = true});
+
   int initializeCalls = 0;
   int cancelAllCalls = 0;
+  int permissionRequests = 0;
   final List<ScheduledCall> scheduled = <ScheduledCall>[];
+  final bool permissionResult;
 
   @override
   Future<void> cancelAll() async {
@@ -96,6 +113,12 @@ class FakeReminderNotificationsDriver implements ReminderNotificationsDriver {
       ),
     );
   }
+
+  @override
+  Future<bool> requestPermissions() async {
+    permissionRequests += 1;
+    return permissionResult;
+  }
 }
 
 class ScheduledCall {