Feat: conversation variable & variable assigner node (#7222)

Signed-off-by: -LAN- <laipz8200@outlook.com>
Co-authored-by: Joel <iamjoel007@gmail.com>
Co-authored-by: -LAN- <laipz8200@outlook.com>

api/tests/unit_tests/models/test_conversation_variable.py

@@ -0,0 +1,25 @@
+from uuid import uuid4
+
+from core.app.segments import SegmentType, factory
+from models import ConversationVariable
+
+
+def test_from_variable_and_to_variable():
+    variable = factory.build_variable_from_mapping(
+        {
+            'id': str(uuid4()),
+            'name': 'name',
+            'value_type': SegmentType.OBJECT,
+            'value': {
+                'key': {
+                    'key': 'value',
+                }
+            },
+        }
+    )
+
+    conversation_variable = ConversationVariable.from_variable(
+        app_id='app_id', conversation_id='conversation_id', variable=variable
+    )
+
+    assert conversation_variable.to_variable() == variable