feat: flatten the agents into injected kwargs

[WilliamBergamin]

Summary

WIP: these changes aim to improve the behavior of Bolt when configured as an "agent"

We are flattening the BoltAgent object in favor of supporting kwargs injection of say_stream, set_status, set_title and set_suggested_prompts

Testing

Coming soon

Category

• slack_bolt.App and/or its core components
• slack_bolt.async_app.AsyncApp and/or its core components
• Adapters in slack_bolt.adapter
• Document pages under /docs
• Others

Requirements

Please read the Contributing guidelines and Code of Conduct before creating this issue or pull request. By submitting, you are agreeing to those rules.

• 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 ./scripts/install_all_and_run_tests.sh after making the changes.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.73%. Comparing base (72a90d2) to head (c30b6fb).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1455      +/-   ##
==========================================
+ Coverage   90.67%   90.73%   +0.06%     
==========================================
  Files         226      229       +3     
  Lines        7205     7256      +51     
==========================================
+ Hits         6533     6584      +51     
  Misses        672      672              

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