Make `Relude.List.permutations` return a `NonEmpty`.

You may observe that any list has at least one permutation. The empty list's only permutation is the empty list itself, so:

```
λ Relude.List.permutations [ ]
[[]]
```

This behaviour is also theoretically sound since permutations of a list are a model of a symmetric group and a group always has at least one element.

It is nicer to have to drop from a `NonEmpty` to a list than to lift from a list to `NonEmpty`, since the latter requires the handling of the spurious case of the list being empty.

Search the Relude.List.permutations definition and its existing tests or usage sites. Confirm the empty-list example remains valid while changing the result type to NonEmpty, then run the relevant test suite and check that callers can still obtain a list when needed.

Written by the indexing model from the issue text.