Label pod with workflow's labels

Currently, the pods of a given workflow are labelled with `workflows.argoproj.io/completed` and `workflows.argoproj.io/workflow`. Could we also add the labels of the workflow to that list, something like:

```bash
workflows.argoproj.io/workflow/label/project = "xxxx"
workflows.argoproj.io/workflow/label/tenant = "xxxx"
```

The issue names no files or tests. Start by locating the code that creates workflow pods and applies the existing completed and workflow labels; trace how workflow labels are available there. Done means pods also contain the requested workflows.argoproj.io/workflow/label/* labels, with coverage for the project and tenant examples.

Written by the indexing model from the issue text.