add support GetMultipleKeys #3974

Job	Run time
Basic Checks	1m 49s
Unit Tests	10m 37s
Integration Tests (raft)	14m 45s
Integration Tests (pvtdata)	13m 19s
Integration Tests (pvtdatapurge e2e)	22m 42s
Integration Tests (ledger)	15m 22s
Integration Tests (lifecycle)	8m 3s
Integration Tests (smartbft)	20m 25s
Integration Tests (discovery gossip devmode pluggable)	11m 12s
Integration Tests (gateway idemix pkcs11 configtx configtxlator)	19m 27s
Integration Tests (sbe nwo msp)	10m 0s
	2h 27m 41s

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