add CTS local time characteristic and use it to provide UTC in DateTimeController

src/components/datetime/DateTimeController.cpp

@@ -36,6 +36,7 @@ void DateTime::SetTime(uint16_t year,
     /* .tm_mon  = */ month - 1,
     /* .tm_year = */ year - 1900,
   };
+
   tm.tm_isdst = -1; // Use DST value from local time zone
   currentDateTime = std::chrono::system_clock::from_time_t(std::mktime(&tm));
 
@@ -50,6 +51,11 @@ void DateTime::SetTime(uint16_t year,
   systemTask->PushMessage(System::Messages::OnNewTime);
 }
 
+void DateTime::SetTimeZone(uint8_t timezone, uint8_t dst) {
+  tzOffset = timezone;
+  dstOffset = dst;
+}
+
 void DateTime::UpdateTime(uint32_t systickCounter) {
   // Handle systick counter overflow
   uint32_t systickDelta = 0;