feat:(github) get_pull_request_comments and get_pull_request_reviews

[monkeydaichan]

** Should be merged #557 **

Description

Add new tools to GitHub MCP server for retrieving pull request review comments and reviews.

Server Details

• Server: github
• Changes to: tools
  • Added get_pull_request_comments tool
  • Added get_pull_request_reviews tool

Motivation and Context

These new tools will enable LLM clients to fetch and analyze pull request review comments and reviews, enabling better code review assistance and collaboration features.

How Has This Been Tested?

• Tested with sample pull requests to verify comment and review retrieval
• Verified correct parsing of review comments and review data
• Confirmed proper error handling for invalid requests

Breaking Changes

No breaking changes. These are new additions that don't affect existing functionality.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the MCP Protocol Documentation
• My changes follows MCP security best practices
• I have updated the server's README accordingly
• I have tested this with an LLM client
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have documented all environment variables and configuration options

Additional context

• Uses existing GitHub API client configuration
• Implements proper error handling for rate limits and API errors
• Returns JSON-formatted response for easy parsing by LLM clients