[WIP] Support rewind feature

[Adib234]

Summary

Introduces a new /rewind command to the Gemini CLI, allowing users to navigate conversation history, revert file changes associated with past interactions, and restart conversations from a selected point

I plan on splitting up the changes over multiple PRs, this PR exists for high-level feedback and any major concerns in design decisions

Details

• Introducing Rewind Feature (packages/cli/src/ui/commands/rewindCommand.tsx, packages/cli/src/ui/components/RewindViewer.tsx, packages/cli/src/ui/utils/rewindFileOps.ts):

  • A new /rewind slash command has been implemented, providing an interactive UI (RewindViewer) to browse previous messages in the conversation history.
  • Users can select a specific message to "rewind" to, effectively resetting the conversation to that point.
  • The feature includes functionality to revert file system changes that were made by the agent after the chosen rewind point, offering multiple options for rewinding.
  • When a rewind occurs, the client's internal history and the context manager are reset, and the UI is updated to reflect the chosen conversation state.

• Integrating Rewind Command (packages/cli/src/services/BuiltinCommandLoader.ts):

  • The rewindCommand is now registered as a built-in command within the BuiltinCommandLoader, making it accessible to users of the Gemini CLI.

Related Issues

Closes #1769

How to Validate

Demo of how it works, all interactions are recorded in the rewind viewer which can be opened by running the slash command /rewind.

https://github.com/user-attachments/assets/eb4d7761-a326-40ef-956d-73d7b19f876f

Pre-Merge Checklist

• [ ] Updated relevant documentation and README (if needed)
• [ ] Added/updated tests (if needed)
• [ ] Noted breaking changes (if any)
• [ ] Validated on required platforms/methods:
  • [ ] MacOS
    • [X] npm run
    • [ ] npx
    • [ ] Docker
    • [ ] Podman
    • [ ] Seatbelt
  • [ ] Windows
    • [ ] npm run
    • [ ] npx
    • [ ] Docker
  • [ ] Linux
    • [ ] npm run
    • [ ] npx
    • [ ] Docker