Refactor text chunking implementation and update configuration

- Moved SentenceTextChunker and SentenceTextChunkerConfig to the utils module for better organization.
- Updated pytest.ini to include the current directory in the Python path.
- Added a new utils module with shared utility helpers.
- Adjusted import paths in the test files to reflect the new location of text chunking classes.

pytest.ini

@@ -1,3 +1,4 @@
 [pytest]
+pythonpath = .
 markers =
-    integration: marks tests that need access to external services
+    integration: marks tests that need access to external services