Python: Multi-agent orchestration: Handoff

[TaoChenOSU]

Motivation and Context

PR for Handoff multi-agent orchestration.
ADR: https://github.com/microsoft/semantic-kernel/blob/main/docs/decisions/0071-multi-agent-orchestration.md
Initial PR: #11993

Description

This PR includes the following:

1. Implementations for the handoff orchestrations
2. Unit tests and samples

Follow up PRs will add the following:

• Magentic One

Contribution Check

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the SK Contribution Guidelines and the pre-submission formatting script raises no violations
• All unit tests pass, and I have added new tests where possible
• I didn't break anyone 😄

[markwallace-microsoft]

Python Unit Test Overview

Tests	Skipped	Failures	Errors	Time
3592	13 💤	0 ❌	0 🔥	1m 49s ⏱️