Show a warning (graphical) if someone changes "Settings" when all the vaults are locked

### Please agree to the following

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

### Summary

Security (potential risk)

### Motivation

I noticed that it is possible changing some app settings without a password.

So when a user, temporarily lose the device control, anyone can changes app behaviors without user awareness.

Put a graphical warning in the home directory (when settings change) resettable only after provided a master password or a local pin.

### Considered Alternatives

_No response_

### Anything else?

_No response_