feat: Add Train feature for Crews (#686)

* feat: add training logic to agent and crew

* feat: add training logic to agent executor

* feat: add input parameter  to cli command

* feat: add utilities for the training logic

* feat: polish code, logic and add private variables

* feat: add docstring and type hinting to executor

* feat: add constant file, add constant to code

* feat: fix name of training handler function

* feat: remove unused var

* feat: change file handler file name

* feat: Add training handler file, class and change on the code

* feat: fix name error from file

* fix: change import to adapt to logic

* feat: add training handler test

* feat: add tests for file and training_handler

* feat: add test for task evaluator function

* feat: change text to fit in-screen

* feat: add test for train function

* feat: add test for agent training_handler function

* feat: add test for agent._use_trained_data

src/crewai/utilities/training_handler.py

@@ -0,0 +1,31 @@
+from crewai.utilities.file_handler import PickleHandler
+
+
+class CrewTrainingHandler(PickleHandler):
+    def save_trained_data(self, agent_id: str, trained_data: dict) -> None:
+        """
+        Save the trained data for a specific agent.
+
+        Parameters:
+        - agent_id (str): The ID of the agent.
+        - trained_data (dict): The trained data to be saved.
+        """
+        data = self.load()
+        data[agent_id] = trained_data
+        self.save(data)
+
+    def append(self, train_iteration: int, agent_id: str, new_data) -> None:
+        """
+        Append new data to the existing pickle file.
+
+        Parameters:
+        - new_data (object): The new data to be appended.
+        """
+        data = self.load()
+
+        if agent_id in data:
+            data[agent_id][train_iteration] = new_data
+        else:
+            data[agent_id] = {train_iteration: new_data}
+
+        self.save(data)