Add utility for Reload Transformers imports cache for development workflow #35508 (#35858)

* Reload transformers fix form cache

* add imports

* add test fn for clearing import cache

* ruff fix to core import logic

* ruff fix to test file

* fixup for imports

* fixup for test

* lru restore

* test check

* fix style changes

* added documentation for usecase

* fixing

---------

Co-authored-by: sambhavnoobcoder <indosambahv@gmail.com>

tests/utils/test_import_utils.py

@@ -0,0 +1,23 @@
+import sys
+
+from transformers.utils.import_utils import clear_import_cache
+
+
+def test_clear_import_cache():
+    # Import some transformers modules
+
+    # Get initial module count
+    initial_modules = {name: mod for name, mod in sys.modules.items() if name.startswith("transformers.")}
+
+    # Verify we have some modules loaded
+    assert len(initial_modules) > 0
+
+    # Clear cache
+    clear_import_cache()
+
+    # Check modules were removed
+    remaining_modules = {name: mod for name, mod in sys.modules.items() if name.startswith("transformers.")}
+    assert len(remaining_modules) < len(initial_modules)
+
+    # Verify we can reimport
+    assert "transformers.models.auto.modeling_auto" in sys.modules