Refactor and clean up codebase by removing unused functions and reorganizing imports

- Removed unused model keys and functions from properties.py.
- Deleted projection.py as its functions were no longer needed.
- Cleaned up model_catalog.py by removing unused model directory function.
- Updated imports in various test files to reflect new module structure.
- Removed deprecated test cases related to image editing tools.
- Added new tests for ONNX runtime provider selection logic.

tests/test_ai_setup.py

@@ -206,4 +206,4 @@ class AiSetupTest(BlenderTestCase):
                     side_effect=AssertionError("UI must not start the Server"),
                 ),
             ):
-                self.assertTrue(properties.required_models_ready())
+                self.assertEqual(properties.ai_status()["missing_models"], ())