Remove tornado and connect the worker to the Streamlit runtime directly

[whitphx]

As the Streamlit core architecture has been drastically changed since v1.12.* decoupling the core runtime and the web server-related parts with PRs including;

• "streamlit.web" package streamlit/streamlit#4956
• streamlit.runtime repackaging (part 1) streamlit/streamlit#5072
• streamlit.Runtime streamlit/streamlit#5136

As a result, now stlite can probably remove Tornado and maintain the runtime object directly.

[whitphx]

Don't forget this: #164 (comment)
when we can remove the ssl module.