Adding long term, short term, entity and contextual memory

src/crewai/memory/entity/entity_memory_item.py

@@ -0,0 +1,12 @@
+class EntityMemoryItem:
+    def __init__(
+        self,
+        name: str,
+        type: str,
+        description: str,
+        relationships: str,
+    ):
+        self.name = name
+        self.type = type
+        self.description = description
+        self.metadata = {"relationships": relationships}