feat(qol): add useful `__repr__` to `WorkspaceRunContext`

Currently the object is a bit opaque. A useful representation would be

```python
<WorkspacRunContext(run_dir="/Absolute/path/to/project", profile="current-profile")>
```

The use of `< >` is convention in Python to show that this `__repr__` can't be used to directly instantiate the object again. 