[dev-cleanup] Refactor perf energy model

[deyuan]

Split class per PIM architecture

[fasiddique]

I am wondering should we create two base classes for performance and energy. Each PIM architecture will extend the base classes as required.

[deyuan]

There are lots of common code between performance and energy formulas, so I'm leaning to bundling perf and energy together for now. Another consideration is that we can first break perf energy models into a few major families, which can be extended or inherited later.

I've created a PR #156 to dev-cleanup branch for early review. Feel free to share any thoughts or ideas.

[deyuan]

Closed with PR #156, #164, #167