Cancel add U2F device process

[kesselb]

Steps to reproduce

1. Go to security
2. Click "Add U2F device"
3. See password confirmation dialog
4. Click "X" to close the dialog

Expected behaviour

See the button Add U2F device button again.

Actual behaviour

A spinner waiting for something.

Might be related to #343

Server configuration

cloud.nextcloud.com

[ChristophWurst]

The problem is that the password confirmation does reject the request. It either resolves or never rejects 😢 I think @skjnldsv worked around this somewhere with a timeout – correct?

[skjnldsv]

🙈 Huuu, I don't think I fixed it properly 🙈
We need to fix this in the library :(