UI change: settings cog icon instead of kebab menu

### 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

On android to access settings user is required to make two clicks: one on kebab menu and then on settings. Kebab menu does not contain any other choices, so why not move settings one level up?

### Motivation

On android to access settings user is required to make two clicks: one on the kebab menu and then on settings. Kebab menu does not contain any other choices, so why not get rid of kebab menu, put cog icon instead and make it accessible with one click? On iOS the settings cog icon is present on the main screen, if I'm not mistaken.

### Considered Alternatives

_No response_

### Anything else?

_No response_