Refactor Recipe creation flow: Directly convert Modifier Instances to Recipe

[rahul-tuli]

This PR refactors the Recipe creation process. The original flow converted Modifier Instances to a recipe string before creating a Recipe. We've simplified this by directly converting Modifier Instances to a Recipe.

• Updated from_modifiers to create a Recipe from Modifier Instances directly.
• Simplified validation for the modifiers parameter.
• Remove relevant unit tests for old flow

Test plan:

Tested using the scripts/recipes from #37.

Added automated e2e tests:

pytest -vv tests/e2e/test_recipe_parsing.py
=========================================================================== test session starts ============================================================================
platform linux -- Python 3.10.12, pytest-8.2.2, pluggy-1.5.0 -- /root/llm-compressor/venv/bin/python3
cachedir: .pytest_cache
rootdir: /root/llm-compressor
configfile: pyproject.toml
plugins: mock-3.14.0, rerunfailures-14.0
collected 3 items                                                                                                                                                          

tests/e2e/test_recipe_parsing.py::test_oneshot[recipe0] PASSED                                                                                                       [ 33%]
tests/e2e/test_recipe_parsing.py::test_oneshot[\nDEFAULT_stage:\n  DEFAULT_modifiers:\n    SmoothQuantModifier:\n      smoothing_strength: 0.8\n      mappings:\n      - - ['re:.*q_proj', 're:.*k_proj', 're:.*v_proj']\n        - re:.*input_layernorm\n      - - ['re:.*gate_proj', 're:.*up_proj']\n        - re:.*post_attention_layernorm\n    GPTQModifier:\n      sequential_update: false\n      targets: Linear\n      scheme: W8A8\n] PASSED [ 66%]
tests/e2e/test_recipe_parsing.py::test_oneshot[/root/llm-compressor/tests/e2e/recipe.yaml] PASSED    

[bfineran]

LGTM pending test

[bfineran]

can we add a new test for a list of modifiers?

[rahul-tuli]

Added Ben!

[Satrat]

Can we add in a test case the tests the bug reported in #37? Reproduced on a tiny model of course. Otherwise LGTM, just make sure to manually run the unit tests before merging since GHA is broken for all the tests requiring runners

[rahul-tuli]

Can we add in a test case the tests the bug reported in #37? Reproduced on a tiny model of course. Otherwise LGTM, just make sure to manually run the unit tests before merging since GHA is broken for all the tests requiring runners

Added e2e tests in last commit and ran them manually:

pytest -vv tests/e2e/test_recipe_parsing.py
=========================================================================== test session starts ============================================================================
platform linux -- Python 3.10.12, pytest-8.2.2, pluggy-1.5.0 -- /root/llm-compressor/venv/bin/python3
cachedir: .pytest_cache
rootdir: /root/llm-compressor
configfile: pyproject.toml
plugins: mock-3.14.0, rerunfailures-14.0
collected 3 items                                                                                                                                                          

tests/e2e/test_recipe_parsing.py::test_oneshot[recipe0] PASSED                                                                                                       [ 33%]
tests/e2e/test_recipe_parsing.py::test_oneshot[\nDEFAULT_stage:\n  DEFAULT_modifiers:\n    SmoothQuantModifier:\n      smoothing_strength: 0.8\n      mappings:\n      - - ['re:.*q_proj', 're:.*k_proj', 're:.*v_proj']\n        - re:.*input_layernorm\n      - - ['re:.*gate_proj', 're:.*up_proj']\n        - re:.*post_attention_layernorm\n    GPTQModifier:\n      sequential_update: false\n      targets: Linear\n      scheme: W8A8\n] PASSED [ 66%]
tests/e2e/test_recipe_parsing.py::test_oneshot[/root/llm-compressor/tests/e2e/recipe.yaml] PASSED    

[rahul-tuli]

Resolves #37 ; and #886