Compute sunrise and sunset only if necessary.

Sunrise and -set must recomputed if one of the following conditions is met:
* The date changed (based on the selected timezone)
* Location (Lat/Lon) changed
* Sunset type changed

So instead of calculating that every minute just do it on update via web interface or date change.

If a new config is uploaded, the DTU gets restarted. There is no need to initiate a recalculation in this case.

src/WebApi_ntp.cpp

@@ -190,6 +190,8 @@ void WebApiNtpClass::onNtpAdminPost(AsyncWebServerRequest* request)
 
     NtpSettings.setServer();
     NtpSettings.setTimezone();
+
+    SunPosition.setDoRecalc(true);
 }
 
 void WebApiNtpClass::onNtpTimeGet(AsyncWebServerRequest* request)
@@ -350,4 +352,4 @@ void WebApiNtpClass::onNtpTimePost(AsyncWebServerRequest* request)
 
     response->setLength();
     request->send(response);
-}
+}