feat: require date_column in training parameters and update documentation

- Made `date_column` a required field in `TrainModelParams`, ensuring it must be present in the input data.
- Updated related documentation in `input-sample.md`, `README.md`, and various test scenarios to reflect the change in requirement.
- Adjusted the handling of `date_format` to default to `yyyy-MM-dd HH:mm:ss` if omitted, enhancing usability.
- Refined test scenarios to include new examples and ensure compliance with the updated parameter structure.

These changes improve the robustness of the model training workflow and clarify the expectations for input data.

docs/test-scenarios/13-angular-test-double-date-column.json

@@ -1,12 +1,12 @@
 {
-  "_description": "Cenário angular-test: CV022 WIT230 com ficheiro double date column e intervalo curto (00:00 a 00:05)",
+  "_description": "Same alternate CSV as scenario 12 (DATA + dd/MM/yyyy); narrow date window for regression coverage. Not a multi-date-column dataset.",
   "experiment_run_id": 1013,
   "variable_columns": [
     "303-WIT-230(Value)"
   ],
   "target_variable": "03CV022/CORRENTE_N_M1_PV(Value)",
   "bucket_name": "model-training",
-  "file_name": "training_data.csv",
+  "file_name": "training_data_dd_mm_yyyy.csv",
   "line_separator": ",",
   "decimal_separator": ".",
   "date_column": "DATA",
@@ -27,7 +27,7 @@
     "rem_static_win": false,
     "static_threshold": null,
     "start_date": "01/05/2022 00:00:00",
-    "end_date": "01/05/2022 00:05:10",
+    "end_date": "31/05/2022 23:59:59",
     "support_filters": {},
     "removed_intervals": []
   },