Add some warning functionality if pop-up blockers prohibits Vipps payments

[JorgenLjones]

Completing a Vipps-donation require a new tab to be opened, and some browsers or their extensions might block this functionality even without alerting the user that it's doing it.

We have at least one account of a user having the second attempt to make a Vipps-donation be blocked (but not the first) and without getting any feedback on why it isn't working.

If we get an error when this happen, we can simply implement some sort of feedback to the user that highlights this with suggestions for how to fix it.
OR
we can give a suggestive warning message like 5 sec after they've pushed the button. If it worked, then they are already busy completing the payment, but if they are waiting the next step they will get the warning message.