Warn users that resources may be left behind if interrupting `dss initialize`, `dss create`

### Why it needs to get done

If a user does:
```
dss create
# wait a few seconds, but not long enough to create the notebook
ctrl+c
```
the `dss create` command is interrupted but likely has created a notebook already. We should warn the users about this. An option could be to add a signal handler in `main.create_notebook_command()` like:

```python
import signal

def create_notebook_command(...):
def signal_handler(sig, frame):
logger.info(f"`dss create` cancelled. This may leave a notebook behind in your environment - use `dss list` to find the notebook and `dss remove {name}` to remove it")
click.get_current_context().exit(1)
signal.signal(signal.SIGINT, signal_handler)

...
```
[ref](https://stackoverflow.com/a/1112350/5394584)

We can add a similar warning to `dss initialize`

### What needs to get done

.

### When is the task considered done

`dss create` and `dss initialize` gracefully handle SIGINT, warning the users of potential consequences and how to address them