ADR Agents - `AgentChat` Serialization Design

[crickman]

Motivation and Context

Users of the Agent Framework are unable to store and later retrieve conversation state when using an AgentChat to coordinate Agent interactions. This limits the ability for an agent conversation to single use as it must be maintained with memory of the process that initiated the conversation.

Formalizing a mechanism that supports serialization and deserialization of any AgentChat class provides an avenue to capture and restore state across multiple sessions as well as compute boundaries.

Description

Design in ADR form for input, exploration of alternatives, and review.

Contribution Checklist

• [X] The PR follows the SK Contribution Guidelines and the pre-submission formatting script raises no violations
• [X] I didn't break anyone :smile: