[Permissions]: provide AND semantics

Currently, the command,
```bash
nephos permission add --for_tags --share_with
```
shares all files with _tag1_ **OR** _tag2_ with the email. We would love to have an option for _tag1_ **AND** _tag2_.

Look at the `nephos permission add` command implementation, likely in a CLI module. Understand how the `--for_tags` flag currently processes tags with OR logic. Add a new flag, perhaps `--and_tags`, to implement AND semantics. Test by creating files with multiple tags and verifying the permission behavior changes.

Vom Indexierungsmodell aus dem Issue-Text verfasst.