Add Exact Deduplication Feature to Preprocessing Pipeline (#2072)

* Add example YAML file for training Mistral using DPO

* added deduplication code

* Add exact deduplication feature and update examples

* Improve deduplication for train/eval overlap

Changed the deduplication function to use a more memory-efficient hashing method. Applied Git suggestions to improve clarity and maintainability.\n\nThe deduplication now handles cases where train and eval datasets have overlapping elements.

* Improve deduplication for train/eval overlap

Changed the deduplication function to use a more memory-efficient hashing method. Applied Git suggestions to improve clarity and maintainability.\n\nThe deduplication now handles cases where train and eval datasets have overlapping elements.

* Apply suggestions from code review

To handle the original case where we do not do deduplication

Co-authored-by: Wing Lian <wing.lian@gmail.com>

* Improve false collision detection to ensure dataset integrity

- Added test cases to simulate and verify handling of forced hash collisions between datasets.
- Ensured that datasets with identical hashes but different content are correctly identified, preventing incorrect deduplication.
- Updated unit tests to include scenarios where collisions occur across both training and evaluation datasets, as well as within a single dataset.

* Moved the constants file to the tests folder

- Relocated `constants.py` to the `tests` folder to improve modularity and maintain a clear separation between source and test files.
- Renamed `cicd/tests.py` to `cicd/cicd_tests.py` to resolve a conflict with `tests/__init__.py`, which caused Mypy to fail due to duplicate module names.
- Updated all references to `cicd.tests` in the codebase to `cicd.cicd_tests` to reflect the renaming and ensure compatibility.
- These changes ensure Mypy passes the pre-commit hook and maintain alignment with the project's structure.

* revert some changes from previous commit and fix relative import

---------

Co-authored-by: Wing Lian <wing.lian@gmail.com>
Co-authored-by: Wing Lian <wing@axolotl.ai>

tests/constants.py

@@ -0,0 +1,32 @@
+# constants.py
+"""
+This module contains constants and configuration dictionaries used for
+datasets and other utilities in the Axolotl project, specifically for testing.
+"""
+# Configuration for Alpaca Messages Dataset
+ALPACA_MESSAGES_CONFIG_OG = {
+    "path": "fozziethebeat/alpaca_messages_2k_dpo_test",
+    "type": "chat_template.default",
+    "chat_template": "llama3",
+    "field_messages": "conversation",
+    "field_chosen": "chosen",
+    "field_rejected": "rejected",
+    "message_field_role": "role",
+    "message_field_content": "content",
+    "roles": {
+        "system": ["system"],
+        "user": ["user"],
+        "assistant": ["assistant"],
+    },
+}
+
+# Revision configuration extending the original
+ALPACA_MESSAGES_CONFIG_REVISION = ALPACA_MESSAGES_CONFIG_OG.copy()
+ALPACA_MESSAGES_CONFIG_REVISION["revision"] = "ea82cff"
+
+
+SPECIAL_TOKENS = {
+    "bos_token": "<s>",
+    "eos_token": "</s>",
+    "unk_token": "<unk>",
+}