<WIP> memory changes

- inlined AgenticSystemInstanceConfig so API feels more ergonomic
- renamed it to AgentConfig, AgentInstance -> Agent
- added a MemoryConfig and `memory` parameter
- added `attachments` to input and `output_attachments` to the response

- some naming changes

llama_toolchain/distribution/datatypes.py

@@ -17,6 +17,7 @@ class Api(Enum):
     inference = "inference"
     safety = "safety"
     agentic_system = "agentic_system"
+    memory = "memory"
 
 
 @json_schema_type