Replace singleton plugin overrides with granular inputs and views

[integraledelebesgue]

Summary

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Type of change

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• Bug fix (fixes incorrect behavior)
• New feature
• Performance improvement
• Documentation change with concrete technical impact
• Style, wording, formatting, or typo-only change

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Why is this change needed?

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What was the behavior or documentation before?

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What is the behavior or documentation after?

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Related issue or discussion (if any)

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Additional context

[integraledelebesgue]

This change is part of the following stack:

• Optimize diagnostics flattening in get_all #9828
  • Skip modules without priv uses when computing unused imports diagnostics #9829
    • Replace singleton file overrides with granular inputs and views #9830
      • Replace singleton crate configs input with granular inputs and views #9831
        • Replace singleton plugin overrides with granular inputs and views #9835 ◀

_{Change managed by git-spice.}

[reviewable-StarkWare]

This change is