Add stress-ng benchmark

[kdh0102]

This PR integrates stress-ng as a KernMLOps benchmark.

Key Changes

• Implemented the stress-ng benchmark in stress_ng.py.
• Added stress-ng as a dependency in the Dockerfile.
• Introduced a benchmark-stress-ng command in the Makefile.
• Provided an example benchmark configuration in defaults.yaml.

Additional Improvements

• Adjusted poll_rate in cli/collect.py.
• Added BenchmarkRunInfoTable to record benchmark start and finish timestamps.
• Fixed type annotations in various Python files (e.g., tlb_perf.py).
  • Will update other files in this PR as needed.