Notify user, when response of Hub Authentication takes a long time

### Please agree to the following

- [X] I have searched [existing issues](https://github.com/cryptomator/cryptomator/issues?q=) for duplicates
- [X] I agree to follow this project's [Code of Conduct](https://github.com/cryptomator/cryptomator/blob/develop/.github/CODE_OF_CONDUCT.md)

### Summary

Develop and implement ux concept for raising user awarness if server response during authentication exceeds a certain threshold.

### Motivation

Some user have different proxy settings for Cryptomator and the default Browser, leading to not being able to authenticate and unlock a vault. #3113 mitigates this issue, but since Cryptomator waits for repsonse from the browser, which requires user interaction, we cannot just time restrict it.

We should develop an UX concept to make the user aware if authentication takes a very long time.

### Considered Alternatives

Time restict whole flow: Since the flow requires user interaction, this would need timeout in minutes.

### Anything else?

Follow up of #3113