refactor: Move events module to crewai.events (#3425)

refactor(events): relocate events module & update imports

- Move events from utilities/ to top-level events/ with types/, listeners/, utils/ structure
- Update all source/tests/docs to new import paths
- Add backwards compatibility stubs in crewai.utilities.events with deprecation warnings
- Restore test mocks and fix related test imports

tests/memory/test_long_term_memory.py

@@ -1,10 +1,10 @@
 import pytest
 from unittest.mock import ANY
 from collections import defaultdict
-from crewai.utilities.events import crewai_event_bus
+from crewai.events.event_bus import crewai_event_bus
 from crewai.memory.long_term.long_term_memory import LongTermMemory
 from crewai.memory.long_term.long_term_memory_item import LongTermMemoryItem
-from crewai.utilities.events.memory_events import (
+from crewai.events.types.memory_events import (
     MemorySaveStartedEvent,
     MemorySaveCompletedEvent,
     MemoryQueryStartedEvent,