Add metadata field to basemessage (#5372) #5126

Job	Run time
format	53s
lint	51s
docs (./packages/autogen-core)	1m 43s
docs-example-check (./packages/autogen-core)	3m 35s
mypy (./packages/autogen-core)	3m 43s
mypy (./packages/agbench)	1m 8s
samples-code-check	57s
mypy (./packages/autogen-ext)	3m 14s
pyright (./packages/autogen-core)	1m 0s
mypy (./packages/autogen-agentchat)	2m 26s
pyright (./packages/agbench)	56s
mypy (./packages/magentic-one-cli)	1m 32s
test (./packages/autogen-core)	1m 1s
pyright (./packages/autogen-ext)	1m 3s
test (./packages/autogen-ext)	4m 10s
pyright (./packages/autogen-agentchat)	1m 15s
test (./packages/autogen-agentchat)	1m 10s
test-grpc	1m 23s
pyright (./packages/magentic-one-cli)	1m 2s
check-proto-changes-python	1m 9s
markdown-code-lint	2m 28s
codecov (./packages/autogen-core)	8s
codecov (./packages/autogen-ext)	9s
codecov (./packages/autogen-agentchat)	12s
codecov (autogen-ext-grpc)	8s
	37m 16s

Provide feedback