Add metrics for performance

[el-dockerr]

This pull request introduces a comprehensive performance metrics testing framework for GhostMem, including new tests, documentation, and automation scripts for both Windows and Linux. These changes make it easier to benchmark GhostMem's compression efficiency, memory savings, and performance overhead, and to track improvements or regressions over time.

Performance Metrics Testing and Documentation:

• Added a new test suite for performance and compression metrics (test_metrics.cpp) and included it in the build process.
• Expanded the README.md with detailed instructions on running all tests and performance metrics tests, and clarified the types of metrics collected. [1] [2]
• Added a summary document (docs/METRICS_SUMMARY.md) to provide a quick reference for running metrics tests, interpreting results, and identifying optimization opportunities.
• Introduced a comprehensive guide (docs/PERFORMANCE_METRICS.md) explaining each metrics test, key performance indicators, how to use metrics for improvements, and integration with CI/CD.
• Updated the roadmap and documentation index in README.md to reference the new metrics guide and clarify test coverage.

Automation Scripts for Performance Testing:

• Added run_metrics.bat (Windows) and run_metrics.sh (Linux) scripts to automate running performance metrics tests, saving results with timestamps, and summarizing key metrics for easy comparison. [1] [2]