Propagate labels from `profile` custom resource to controller-generated namespace

/kind feature

**Why you need this feature:**
We use the profile operator directly instead of pathing through the UI. We want end user namespaces to have specific labels (that identify various things about the user). [This code](https://github.com/kubeflow/kubeflow/blob/master/components/profile-controller/controllers/profile_controller.go#L137) lets administrators set **global** namespace labels, but there's no mechanism to pass custom-resource-specific, non-global labels.

**Describe the solution you'd like:**
The simplest way to implement this is to just propagate labels from the `profile` custom resource to the corresponding namespace. It's a one line change to the controller logic.

**Anything else you would like to add:**
I'll submit a PR momentarily.

Start in components/profile-controller/controllers/profile_controller.go at the namespace-label logic linked in the issue. Trace how the profile custom resource and generated namespace are handled, then verify that profile-specific labels are propagated without changing the global-label behavior; the payload names no test file to run.

Written by the indexing model from the issue text.