Modular Integration Test Framework with DeepSeek-v3 Support

[wwwjn]

Integration Tests Restructuring

• Split tests into two sets:

  1. Depth Test: Use llama3 model, to test all the main components of torchtitan are functioning as expected
  2. Breath Test: As we are supporting more models in torchtitan core, setup parallelsim related tests for each model, to test model architecture / args related changes. Make sure the Integration test implementation is easy to extend to new models.

• Moved integration test files from the root directory to a dedicated tests/integration_tests/ directory

• Added a base configuration file base_config.toml for integration tests, as most of the train_configs shared 90% same settings

• Remove "use_for_integration_test" field in train configs. Change to by default using "debugmodel" flavor for integration tests.