feat(github): optimize GitHub metrics collection and processing

This commit introduces several optimizations and improvements to the GitHub
metrics collection and processing:

1. Implement concurrent processing of repositories and pull requests
2. Add connection pooling and semaphore to manage API rate limits
3. Optimize data fetching by collecting PR data in batches
4. Improve error handling and logging for better debugging
5. Refactor metrics update functions for better modularity
6. Add missing bottleneck metrics tracking
7. Enhance collaboration metrics with review participation rate
8. Optimize time metrics calculation, including deployment frequency
9. Improve code organization and readability

These changes aim to significantly improve the performance and reliability
of the GitHub metrics collection process, especially for large repositories
and organizations.

Author: pimoussTO