docs - adds chat_stream helper to python sdk docs (removing from bolt-py)

[lukegalbraithrussell]

Summary

This is a result of say_stream being added to Bolt; shifts this helper down. This can go out whenever we want as long as we don't mind duplicating content about the python sdk helper. Otherwise, wait until this Bolt PR goes out

Testing

Category

• slack_sdk.web.WebClient (sync/async) (Web API client)
• slack_sdk.webhook.WebhookClient (sync/async) (Incoming Webhook, response_url sender)
• slack_sdk.socket_mode (Socket Mode client)
• slack_sdk.signature (Request Signature Verifier)
• slack_sdk.oauth (OAuth Flow Utilities)
• slack_sdk.models (UI component builders)
• slack_sdk.scim (SCIM API client)
• slack_sdk.audit_logs (Audit Logs API client)
• slack_sdk.rtm_v2 (RTM client)
• /docs (Documents)
• /tutorial (PythOnBoardingBot tutorial)
• tests/integration_tests (Automated tests for this library)

Requirements

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.
• I've run python3 -m venv .venv && source .venv/bin/activate && ./scripts/run_validation.sh after making the changes.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.99%. Comparing base (4547d73) to head (9466e7c).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1846   +/-   ##
=======================================
  Coverage   83.99%   83.99%           
=======================================
  Files         117      117           
  Lines       13253    13253           
=======================================
  Hits        11132    11132           
  Misses       2121     2121           

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[mwbrooks]

✅ Looking good! I left a minor question/suggestion. Thanks for refactoring the docs around!

I vote merging now, since the duplication will be naturally sorted out and this adds value today.