Reset right bar content on dataset and notebook selection

[Irozuku]

Summary

This pull request improves UI state management in the DatasetNotebookLeftBar component. When a user selects a different dataset or notebook, the right sidebar content is now cleared to prevent stale or irrelevant information from being displayed.

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Type of Change

Check all that apply like this [x]:

• Backend change
• Frontend change
• CI / Workflow change
• Build / Packaging change
• Bug fix
• Documentation

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Changes (by file)

Briefly list the important modified files and what was done.

• DashAI/front/src/components/notebooks/DatasetNotebookLeftBar.jsx:
  • Added calls to setRightBarContent(null) in dataset and notebook selection handlers to clear the right sidebar when a new item is selected.
  • Included setRightBarContent from the useDatasetsAndNotebooks hook to enable updating the sidebar state.

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Testing (optional)

• Select different datasets and notebooks and verify that the right sidebar content is cleared when dataloader configuration was being displayed.
• Confirm no unintended side effects in other sidebar interactions.