JSON parsing: always fix all incoming json when using _manual_json

[MarkJGx]

Description

This change set adds non-LLM-based JSON malformity handling as a preliminary step before using the more resource-intensive LLM-based fixup.

More Details

While running GraphRAG with a local Ollama model, I noticed frequent malformed JSON responses from LLM requests, significantly slowing down the process on an M1 Max MacBook. In a fast, parallel cloud inference system, this issue is manageable, but locally it becomes a bottleneck. After indexing, I found 140 instances of JSON parsing failures.

The json_repair library effectively fixed the malformed JSON in my tests. I opted not to delve into the specific parsing failure cases, as they are mainly LLM-related and predicting every edge case is impractical. This library should be robust enough to handle most local LLM faults.

Related Issues

• https://github.com/microsoft/graphrag/issues/345

Proposed Changes

• Add json_repair as a new Poetry dependency.
  • https://pypi.org/project/json-repair/
• Use json_repair for initial JSON repair in _manual_json, with a fallback to the LLM.
• Apply JSON repair when graph search JSON parsing fails.

Checklist

• [x] Tested these changes locally.
• [x] Reviewed the code changes.
• [x] Updated documentation (if necessary).
• [ ] Added appropriate unit tests (if applicable).