Configure Project Structure and Refactor Imports for et_replay

[TaekyungHeo]

Summary

• Created pyproject.toml for package setup and script entry points.
• Refactored import paths in et_replay.py and validate_trace.py to align with new package structure.
• Added .gitignore to exclude build/ and et_replay.egg-info/.

Test Plan

$ cd et_replay

$ pip install .
Processing /Users/theo/param/et_replay
  Installing build dependencies ... done
  Getting requirements to build wheel ... done
  Installing backend dependencies ... done
  Preparing metadata (pyproject.toml) ... done
Building wheels for collected packages: et_replay
  Building wheel for et_replay (pyproject.toml) ... done
  Created wheel for et_replay: filename=et_replay-1.0.0-py3-none-any.whl size=59701 sha256=8bf68250c2b168b1e67ab75ea3d2059d018e2738ec9437bc712c2e3f00da6511
  Stored in directory: /private/var/folders/z0/c9mq5j4s6n14n0_gs7nlt6mc0000gp/T/pip-ephem-wheel-cache-_rrl79h0/wheels/3b/3f/aa/d3fc853f83c22c6f3eeb09763570c2cc8031a1a414cb3c18b6
Successfully built et_replay
Installing collected packages: et_replay
  Attempting uninstall: et_replay
    Found existing installation: et_replay 1.0.0
    Uninstalling et_replay-1.0.0:
      Successfully uninstalled et_replay-1.0.0
Successfully installed et_replay-1.0.0

$ validate_trace ~/Downloads/llama_pytorch24.05/megatron_et_0.json 
num ops = 51343, num comms = 32, num triton ops = 0
Trace validation result =  False

$ et_replay                                                       
Traceback (most recent call last):
  File "/Users/theo/venv/bin/et_replay", line 5, in <module>
    from et_replay.tools.et_replay import main
  File "/Users/theo/venv/lib/python3.10/site-packages/et_replay/tools/et_replay.py", line 15, in <module>
    from ..lib.et_replay_utils import (
  File "/Users/theo/venv/lib/python3.10/site-packages/et_replay/lib/et_replay_utils.py", line 5, in <module>
    from fbgemm_gpu.split_table_batched_embeddings_ops import PoolingMode, WeightDecayMode
ModuleNotFoundError: No module named 'fbgemm_gpu'