Python: Introduce Agent group chat functionality

[moonbox3]

Motivation and Context

In the next phase of the agent work in Python, we are to introduce the ability to have agents interact with each other. Agent group chat allows developers to create richer and more dynamic agent interactions.

Description

This PR introduces the following:

• Agent group chat functionality via an agent_chat base class that forms the foundation for group chats. An agent_group_chat class extends that underlying functionality and provides an entry point to kick off the group chat either via invoking the chat for the defined agents, or specifying if a provided agent is to join the existing chat.
• The required channels for the chat completion agent and assistant agent to properly chat together
• Adds more concept samples and getting started with agent samples to enrich the onboarding experiencing for those wanting to see the capability of agents and agent group chat.
• Adds unit test for near 100% coverage
• Updates some existing imports for agents, which try and make the required import experience more intuitive.
• Introduces assistant agent abstractions for working with files and vector stores so we don't directly expose the underlying client types.
• Closes Python Agents - Add samples for step 9 -12 to GettingStartedWithAgents #7966
• Closes Python: implement agent group chat functionality #7577

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 Test Coverage Report

File	Stmts	Miss	Cover	Missing
semantic_kernel
kernel.py	199	47	76%	150, 161, 165, 315–318, 425, 439–482
semantic_kernel/agents/group_chat
agent_chat.py	108	1	99%	91
agent_group_chat.py	67	2	97%	113, 135
broadcast_queue.py	72	1	99%	35
semantic_kernel/agents/open_ai
open_ai_assistant_base.py	361	3	99%	243, 321–322
semantic_kernel/connectors/ai/anthropic/services
anthropic_chat_completion.py	94	25	73%	171–181, 196–205, 222–236
semantic_kernel/connectors/ai/azure_ai_inference/services
azure_ai_inference_chat_completion.py	149	3	98%	170, 320, 436
semantic_kernel/connectors/ai/embeddings
embedding_generator_base.py	8	1	88%	50
semantic_kernel/connectors/ai/google
shared_utils.py	39	2	95%	97, 119
semantic_kernel/connectors/ai/google/google_ai/services
google_ai_chat_completion.py	148	3	98%	151, 263, 297
utils.py	63	3	95%	139, 157–162
semantic_kernel/connectors/ai/google/vertex_ai/services
utils.py	65	3	95%	141, 159–164
vertex_ai_chat_completion.py	148	3	98%	145, 256, 290
semantic_kernel/connectors/ai/hugging_face/services
hf_text_completion.py	54	3	94%	97, 105, 136
hf_text_embedding.py	32	5	84%	79–83
semantic_kernel/connectors/memory/azure_ai_search
azure_ai_search_collection.py	87	2	98%	150, 152
semantic_kernel/connectors/memory/redis
redis_collection.py	160	2	99%	146, 316
utils.py	45	11	76%	145–146, 164, 166, 173–188
semantic_kernel/connectors/openapi_plugin
openapi_manager.py	58	2	97%	110–111
openapi_parser.py	88	1	99%	127
openapi_runner.py	105	2	98%	181–182
semantic_kernel/connectors/openapi_plugin/models
rest_api_operation.py	129	1	99%	242
semantic_kernel/contents
function_call_content.py	97	1	99%	201
semantic_kernel/data
vector_store_record_collection.py	249	19	92%	410, 470–474, 482–486, 526–529, 536–539
vector_store_record_utils.py	26	2	92%	50, 52
semantic_kernel/functions
kernel_function_decorator.py	98	1	99%	102
kernel_function_from_method.py	96	1	99%	153
kernel_function_from_prompt.py	154	7	95%	165–166, 180, 201, 219, 239, 322
kernel_plugin.py	187	2	99%	472, 475
semantic_kernel/planners
plan.py	234	45	81%	54, 163–165, 197, 214–227, 264, 269, 277–278, 288–291, 308, 313, 329, 332–337, 355, 360, 363, 365, 372, 386–388, 393–397
semantic_kernel/planners/function_calling_stepwise_planner
function_calling_stepwise_planner.py	116	4	97%	145, 189–190, 198
semantic_kernel/planners/sequential_planner
sequential_planner.py	64	6	91%	71, 75, 109, 125, 134–135
sequential_planner_extensions.py	50	9	82%	31–32, 56, 110–124
sequential_planner_parser.py	77	12	84%	66–74, 93, 117–120
semantic_kernel/schema
kernel_json_schema_builder.py	119	5	96%	50, 84, 206, 210–211
semantic_kernel/template_engine/blocks
code_block.py	77	1	99%	119
named_arg_block.py	43	1	98%	98
semantic_kernel/utils/telemetry
decorators.py	113	4	96%	232, 240, 243, 252
user_agent.py	16	2	88%	18–19
TOTAL	10668	248	98%

Python Unit Test Overview

Tests	Skipped	Failures	Errors	Time
2367	1 💤	0 ❌	0 🔥	52.482s ⏱️

[eavanvalkenburg]

Small note, not blocking! awesome stuff!