Add sample distributed group chat notebook #372

Job	Run time
format	20s
lint	28s
mypy (./packages/autogen-core)	1m 28s
docs (./packages/autogen-core)	45s
mypy (./packages/autogen-magentic-one)	41s
mypy (./packages/agbench)	24s
pyright (./packages/autogen-core)	34s
mypy (./packages/autogen-ext)	50s
test (./packages/autogen-core)	39s
pyright (./packages/autogen-magentic-one)	27s
mypy (./packages/autogen-agentchat)	45s
test (./packages/autogen-magentic-one)	52s
pyright (./packages/agbench)	23s
test (./packages/autogen-ext)	1m 13s
pyright (./packages/autogen-ext)	30s
check-proto-changes-python	26s
test (./packages/autogen-agentchat)	24s
pyright (./packages/autogen-agentchat)	26s
	11m 35s

Provide feedback