Library use: Turn off the Halo spinner

## Problem
The Halo spinner is nice when using `croud` interactively, but it is detrimental when using it as a library. In this case, we faced problems within a Jupyter Notebook environment, because the notebook cell rendering gets offended by the rendering of the spinner.

## Suggestion
Please only ever use interactivity components when `is_tty() is True`. In this spirit, _absolutely_ don't start the `HALO` at module-scope level already, but initialize/configure it at _runtime instead_.

## References

> We had to turn off the Halo spinner currently used in `croud`, because it did not work well within a Jupyter Notebook environment.
> - https://github.com/crate/cratedb-toolkit/pull/81#discussion_r1397882930