Notify battery level every 10 minutes when connected to a BLE host.

Refactor battery percent : only use uint8_t to store the battery % remaining.

src/displayapp/screens/WatchFaceDigital.h

@@ -45,7 +45,7 @@ namespace Pinetime {
         Pinetime::Controllers::DateTime::Days currentDayOfWeek = Pinetime::Controllers::DateTime::Days::Unknown;
         uint8_t currentDay = 0;
 
-        DirtyValue<int> batteryPercentRemaining {};
+        DirtyValue<uint8_t> batteryPercentRemaining {};
         DirtyValue<bool> bleState {};
         DirtyValue<std::chrono::time_point<std::chrono::system_clock, std::chrono::nanoseconds>> currentDateTime {};
         DirtyValue<bool> motionSensorOk {};