adds integration test for the InMemoryRuntime #2332

Job	Run time
lint	47s
format	49s
mypy (./packages/autogen-core)	2m 7s
pyright (./packages/autogen-core)	1m 7s
mypy (./packages/autogen-magentic-one)	1m 21s
pyright (./packages/autogen-magentic-one)	58s
check-proto-changes-python	1m 19s
mypy (./packages/agbench)	1m 2s
pyright (./packages/agbench)	1m 2s
docs (./packages/autogen-core)	1m 31s
pyright (./packages/autogen-ext)	1m 8s
mypy (./packages/autogen-ext)	1m 39s
pyright (./packages/autogen-agentchat)	52s
mypy (./packages/autogen-agentchat)	1m 5s
docs-example-check (./packages/autogen-core)	2m 14s
test (./packages/autogen-core)	1m 0s
test (./packages/autogen-magentic-one)	1m 26s
test (./packages/autogen-ext)	2m 6s
test (./packages/autogen-agentchat)	56s
	24m 29s

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