View last sync and next sync run from syncer

### Please agree to the following

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

### Summary

In the Admin section, view last sync and next sync run from syncer

### Motivation

As an admin, it is good to know when the last user/group sync was run and when the next one will be run, e.g. if users are not showing up in the 'Add Members' section.

Also display information if the last run was a failure.

### Considered Alternatives

_No response_

### Anything else?

_No response_