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

tests/utilities/test_training_handler.py

@@ -0,0 +1,42 @@
+import os
+import unittest
+
+from crewai.utilities.training_handler import CrewTrainingHandler
+
+
+class TestCrewTrainingHandler(unittest.TestCase):
+    def setUp(self):
+        self.handler = CrewTrainingHandler("trained_data.pkl")
+
+    def tearDown(self):
+        os.remove("trained_data.pkl")
+        del self.handler
+
+    def test_save_trained_data(self):
+        agent_id = "agent1"
+        trained_data = {"param1": 1, "param2": 2}
+        self.handler.save_trained_data(agent_id, trained_data)
+
+        # Assert that the trained data is saved correctly
+        data = self.handler.load()
+        assert data[agent_id] == trained_data
+
+    def test_append_existing_agent(self):
+        train_iteration = 1
+        agent_id = "agent1"
+        new_data = {"param3": 3, "param4": 4}
+        self.handler.append(train_iteration, agent_id, new_data)
+
+        # Assert that the new data is appended correctly to the existing agent
+        data = self.handler.load()
+        assert data[agent_id][train_iteration] == new_data
+
+    def test_append_new_agent(self):
+        train_iteration = 1
+        agent_id = "agent2"
+        new_data = {"param5": 5, "param6": 6}
+        self.handler.append(train_iteration, agent_id, new_data)
+
+        # Assert that the new agent and data are appended correctly
+        data = self.handler.load()
+        assert data[agent_id][train_iteration] == new_data