Describe the feature or problem you’d like to solve

Currently, the GH MCP server does not support creating Issue Types of an organization.

Proposed solution

Add tools for listing, creating, updating, and deleting issue types of an organization. The go-github package has the API support for issue types.

Additional context

A few types (Task, Bug, and Feature) comes by default in an Organization. There are open issues related to Issue Types while creating and updating issues.

Related issues: #230 #409