[FEATURE] Multiagent takeSnapshot/loadSnapshot

[JackYPCOnline]

Problem Statement

We already have agent level takeSnapshot/loadSnapshot, we also want to have this in multiagent pattern.
This feature is also a blocker for multiagent session management.

Proposed Solution

Add it.

Use Case

It is an important piece for multiagent state durability

Alternatives Solutions

No response

Additional Context

No response