Preview CLI command

It would be nice to have a `preview` command for the CLI similar to what is present in the [Cottontail CLI](https://github.com/vitrivr/cottontaildb/blob/master/cottontaildb-cli/src/main/kotlin/org/vitrivr/cottontail/cli/query/PreviewEntityCommand.kt).

This should probably mirror the Cottontail CLI syntax, so it should be `query preview` and not `entity preview`.

