Expose all declared GitHub tools

[Cubbee]

Description

There are a lot of commands declared in Github server readme, that were not exposed.
It caused clients ignoring the tools.

Server Details

• Server: github
• Changes to: index.ts

Motivation and Context

This change allows client to call additional tools that were already implemented, but not exposed, like get_pull_request_comments

How Has This Been Tested?

I've tested the added tools via Cursor, it works as expected

Breaking Changes

No

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

[JuanJo-RC]

This change is very useful because it exposes additional tools that were already implemented in the server but were not accessible to clients. Thank you Cubbee