Fix #2787: Add direct kickoff methods to CrewBase instances

Co-Authored-By: Joe Moura <joao@crewai.com>

tests/reproduce_2787.py

@@ -0,0 +1,36 @@
+from crewai import Agent, Crew, Task, Process
+from crewai.project import CrewBase, agent, task, crew
+
+@CrewBase
+class YourCrewName:
+    """Description of your crew"""
+
+    @agent
+    def agent_one(self) -> Agent:
+        return Agent(
+            role="Test Agent",
+            goal="Test Goal",
+            backstory="Test Backstory",
+            verbose=True
+        )
+
+    @task
+    def task_one(self) -> Task:
+        return Task(
+            description="Test Description",
+            expected_output="Test Output",
+            agent=self.agent_one()
+        )
+
+    @crew
+    def crew(self) -> Crew:
+        return Crew(
+            agents=[self.agent_one()],
+            tasks=[self.task_one()],
+            process=Process.sequential,
+            verbose=True,
+        )
+
+c = YourCrewName()
+result = c.kickoff()
+print(result)