feat: modal tool execution - NO FEATURE FLAGS USES MODAL [LET-4357] (#5120)

* initial commit

* add delay to deploy

* fix tests

* add tests

* passing tests

* cleanup

* and use modal

* working on modal

* gate on tool metadata

* agent state

* cleanup

---------

Co-authored-by: Letta Bot <noreply@letta.com>

tests/test_client.py

@@ -395,7 +395,7 @@ def test_function_always_error(client: Letta):
     assert response_message.status == "error"
     # TODO: add this back
     # assert "Error executing function testing_method" in response_message.tool_return, response_message.tool_return
-    assert "ZeroDivisionError: division by zero" in response_message.stderr[0]
+    assert "division by zero" in response_message.stderr[0]
 
     client.agents.delete(agent_id=agent.id)