Spacy-streamlit

> 🌙 **This release is a pre-release and requires [spaCy v3](https://nightly.spacy.io/usage/v3) (nightly).**

* Upgrade to latest Streamlit and use columns and expander widgets for controls.
* Move visualizer-specific settings into main content instead of sidebar.
* Add `show_config` setting to show `config.cfg` of currently loaded model.
* Add `default_model` setting to specify option to auto-select in dropdown.
* Add `show_pipeline_info` setting to toggle pipeline description in sidebar.
* Update default token attributes to include `Token.morph` and `Token.is_sent_start`.
* Add `get_default_text` callback to generate default text based on `nlp` object (e.g. language).

> 🌙 **This release is a pre-release and requires [spaCy v3](https://nightly.spacy.io/usage/v3) (nightly).**

* Upgrade to latest Streamlit and use columns and expander widgets for controls.
* Move visualizer-specific settings into main content instead of sidebar.
* Add `show_config` setting to show `config.cfg` of currently loaded model.
* Add `default_model` setting to specify option to auto-select in dropdown.
* Add `show_pipeline_info` setting to toggle pipeline description in sidebar.
* Update default token attributes to include `Token.morph` and `Token.is_sent_start`.

- Clean up custom CSS for color theme.
- Support both lists of model names as well as a dict mapping models to descriptions to display in the dropdown.
- Add `show_visualizer_select` option to allow user to toggle displayed visualizers (based on the specified options).
- Use checkboxes instead of buttons for JSON `Doc` and model meta.

- Add `key` argument to widgets to prevent problem with duplicate widgets.
- Add `colors` parameter to `ner_visualizer`.

Thanks to Jcharis, yagays, pmbaumgartner, andfanilo and discdiver for the pull requests!