Punet IREE Testing

[saienduri]

We currently https://github.com/iree-org/iree/tree/main/experimental/regression_suite/shark-test-suite-models/sdxl and https://github.com/iree-org/iree/tree/main/experimental/benchmarks/sdxl in IREE project for testing sdxl on every commit for fp16 model and int8 model with fp16/fp8 attention. We are currently not testing the spec file (due to compiler productization discussions), so the performance testing doesn't fully correlate with what we track in the MLPerf CI. Also, currently, there is no performance testing for the int8 punet model.

Next steps would be to add both of these as a not required to pass presubmit item in IREE CI, so it is easy for Nithin to track and days are not wasted chasing down regressions. Eventual goal is to completely migrate from using spec files and have it baked into the compiler itself.