FSDP1 -> FSDP2 (#2760)

* FSDP2 args migration implementation

This commit implements the migration to FSDP2 arguments including:
- FSDP2 support with LoRA training
- DPO integration with FSDP2
- Model loading fixes and refactoring
- CPU offloading and PEFT handling
- Test updates and CI improvements
- Bug fixes for dtype errors and various edge cases

tests/e2e/utils.py

@@ -77,6 +77,18 @@ def require_torch_2_6_0(test_case):
     return unittest.skipUnless(is_min_2_6_0(), "test requires torch>=2.6.0")(test_case)
 
 
+def require_torch_2_7_0(test_case):
+    """
+    Decorator marking a test that requires torch >= 2.7.0
+    """
+
+    def is_min_2_7_0():
+        torch_version = version.parse(torch.__version__)
+        return torch_version >= version.parse("2.7.0")
+
+    return unittest.skipUnless(is_min_2_7_0(), "test requires torch>=2.7.0")(test_case)
+
+
 def require_torch_lt_2_6_0(test_case):
     """
     Decorator marking a test that requires torch < 2.6.0