fix(storybook): Prevent Slot.Consumer error in investigations stories

[sentry]

The `InvestigationsPage` component uses ``, which is a `Slot.Consumer` for the "title" slot. In the Storybook stories for `InvestigationsPage` (`static/app/views/investigations/index.stories.tsx`), the component was rendered without the necessary `Slot.Provider` in its ancestor tree.

This PR fixes the issue by importing TopBar and wrapping the InvestigationsPage instances in the Storybook stories with <TopBar.Slot.Provider>. This ensures that the Slot.Consumer has the required context, preventing the "<Slot.Consumer> for slot "title" rendered without a <Slot.Provider>" error.

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Fixes JAVASCRIPT-39VW

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[github-actions]

Story previews

Preview the stories changed in this PR on the Vercel deployment:

• app/views/investigations/index.stories.tsx

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