Consider using `k8s.io/apimachinery/pkg/util/sets` instead of `map` of empty `struct`s for sets

It was proposed to switch from `maps` for empty `struct`s such as this:

```go
visited := map[deppy.Identifier]struct{}{}
```

to using `k8s.io/apimachinery/pkg/util/sets` for sets. Example:

```go
sets.New[deppy.Identifier]()
```

_Originally posted by @stevekuznetsov in https://github.com/operator-framework/operator-controller/pull/453#discussion_r1354998763_
            