log entering/leaving realtime

this is useful for debugging.
ftr, using deinit() seems to be file as this is called through
"Automatic Reference Counting", not garbage collection at a later point
(https://docs.swift.org/swift-book/documentation/the-swift-programming-language/deinitialization/ )

deltachat-ios/Controller/WebxdcViewController.swift

@@ -291,6 +291,7 @@ class WebxdcViewController: WebViewViewController {
     }
 
     deinit {
+        logger.info("⬅️ leave realtime by deinit")
         dcContext.leaveWebxdcRealtime(messageId: messageId)
     }
 
@@ -516,6 +517,7 @@ extension WebxdcViewController: WKScriptMessageHandler {
             }
 
         case .sendRealtimeAdvertisement:
+            logger.info("➡️ send realtime advertisement")
             dcContext.sendWebxdcRealtimeAdvertisement(messageId: messageId)
 
         case .sendRealtimeData:
@@ -524,6 +526,7 @@ extension WebxdcViewController: WKScriptMessageHandler {
             }
 
         case .leaveRealtime:
+            logger.info("⬅️ leave realtime by xdc request")
             dcContext.leaveWebxdcRealtime(messageId: messageId)
         }
     }