Hint if “Allow forward URL requests to external intents” or similar is deactivated.

[DwainZwerg]

Due to #346:
Currently, we already indicate when JavaScript is disabled (yes, this is easier to implement). Is it somehow also possible to detect if the forwardURL was not forwarded to Obtainium or to detect that the option is disabled in the respective browser? If so, it would be good to display a message that the function must be activated.

If it is not possible for us to detect this, it might be a good idea to give a browser popup that pops up after someone has clicked on “Add App”. After confirming the browser popup, this popup should then be turned off in the browser's website settings.