Improve speedup display for TorchAO dashboard

[huydhn]

There are several requests for TorchAO dashboard:

1. To show different speedups:
   a. speedup autoquant + compile v.s compile (what the dashboard is currently showing)
   b. speedup compile v.s. eager speedup autoquant v.s. eager
2. To be able to see the speedup between the base commit and the new commit like what we have in https://hud.pytorch.org/benchmark/compilers

cc @jerryzh168 @yangw-dev