various small fixes

- clean up webproxy getExtUrl
- bugfix init multicast on wifi reconnect
- add ip address of remote AP that's taken over a tag
- renamed button 'edit contentFS' to 'file system'

ESP32_AP-Flasher/src/web.cpp

@@ -497,7 +497,6 @@ void init_web() {
 
     server.on("/sysinfo", HTTP_GET, handleSysinfoRequest);
     server.on("/check_file", HTTP_GET, handleCheckFile);
-    server.on("/getexturl", HTTP_GET, handleGetExtUrl);
     server.on("/rollback", HTTP_POST, handleRollback);
     server.on("/update_actions", HTTP_POST, handleUpdateActions);
     server.on("/update_ota", HTTP_POST, [](AsyncWebServerRequest *request) {