Add Token Streaming in AGS , Support Env variables #5121

Job	Run time
lint	52s
mypy (./packages/autogen-core)	3m 32s
pyright (./packages/autogen-core)	1m 2s
mypy (./packages/agbench)	1m 10s
pyright (./packages/agbench)	58s
mypy (./packages/autogen-ext)	3m 5s
pyright (./packages/autogen-ext)	1m 7s
mypy (./packages/autogen-agentchat)	1m 39s
pyright (./packages/autogen-agentchat)	1m 11s
mypy (./packages/magentic-one-cli)	1m 22s
pyright (./packages/magentic-one-cli)	57s
docs (./packages/autogen-core)	1m 40s
docs-example-check (./packages/autogen-core)	3m 56s
markdown-code-lint	2m 50s
samples-code-check	1m 12s
test (./packages/autogen-core)	1m 0s
test-grpc	1m 22s
test (./packages/autogen-ext)	4m 26s
test (./packages/autogen-agentchat)	1m 5s
check-proto-changes-python	1m 18s
format	1m 1s
codecov (./packages/autogen-core)	13s
codecov (./packages/autogen-ext)	9s
codecov (./packages/autogen-agentchat)	10s
codecov (autogen-ext-grpc)	9s
	37m 26s

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