Fix/deprioritize image requests (#638)

* Use "fetch" instead of "axios"

Axios does not support prioritizing requests

* Deprioritize image requests

The browser requests images (<img>) with low priority by default.
Due to switching to loading images via axios (f852ce70e7), the image requests had the same priority as other requests and thus blocked e.g. xhr requests

src/screens/settings/ServerSettings.tsx

@@ -88,7 +88,6 @@ export const ServerSettings = () => {
     const handleServerAddressChange = (address: string) => {
         const serverBaseUrl = address.replaceAll(/(\/)+$/g, '');
         setServerAddress(serverBaseUrl);
-        requestManager.updateClient({ baseURL: serverBaseUrl });
     };
 
     const updateSetting = <Setting extends keyof ServerSettingsType>(