feat: add deferred execution mode to interactive table

[shuoweil]

** This PR is not ready for review. **

Introduces "Deferred Execution Mode" for the interactive Table Widget. By default, the widget now displays a preview with a "Run Query and Display Widget" button instead of immediately executing potentially expensive BigQuery jobs. This enhances cost control and prevents accidental large data fetches in interactive environments like Jupyter Notebooks.

Key Changes

• Deferred Execution: TableWidget now defaults to a deferred state. Users must explicitly click "Run Query" to execute the job and load data.
• Global Configuration: Added bigframes.options.display.anywidget_deferred (default: True) to allow users to toggle this behavior globally or programmatically.
• UI Experience:
  • Added a clear "preview" state for deferred widgets.
  • Fixed visual "shaking" issues during table re-renders.
  • Improved height stabilization to prevent layout shifts.
• Documentation: Updated notebooks/dataframes/anywidget_mode.ipynb with examples of deferred mode and how to disable it.

Verified at

• vs code notebook: https://screencast.googleplex.com/cast/NDc1MTAyOTYzMDQwMjU2MHxmOWE1NzQwNy0yOQ
• colab notebook: https://screencast.googleplex.com/cast/NTUyNzU3NjIyNjI5OTkwNHwwMjY2ZmQ4Yy0xYQ

Fixes #<460865443> 🦕

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