Add worker_commands namespace capability (#771)

## What
Add `worker_commands` bool field to capabilities.

## Why
This feature requires SDK to implicitly create a new task queue and
poller per process. Preferable to do this in a controlled manner.

## How did you test it?
Build

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Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: rkannan82