[Misc] Update usage with mooncake lib for kv transfer

[ShangmingCai]

We have refactored the mooncake lib and updated the interface to make it formatted in the Python style.

Also, Mooncake supports pip install now.

pip3 install mooncake-transfer-engine

So this PR updates the interfaces related to the usage of the mooncake lib.

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[KuntaiDu]

LGTM!