Merge RootCoord, DataCoord And QueryCoord into MixCoord
Make Session into one
issue : https://github.com/milvus-io/milvus/issues/37764
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Signed-off-by: Xianhui.Lin <xianhui.lin@zilliz.com>
issue: #38399
We want to support broadcast operation for both streaming and msgstream.
But msgstream can be only sent message from rootcoord and proxy.
So this pr move the streamingcoord to rootcoord to make easier
implementation.
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Signed-off-by: chyezh <chyezh@outlook.com>