add support GetMultipleKeys #3972

Job	Run time
Basic Checks	2m 3s
Unit Tests	10m 36s
Integration Tests (raft)	17m 17s
Integration Tests (pvtdata)	11m 53s
Integration Tests (pvtdatapurge e2e)	22m 25s
Integration Tests (ledger)	14m 44s
Integration Tests (lifecycle)	9m 17s
Integration Tests (smartbft)	23m 5s
Integration Tests (discovery gossip devmode pluggable)	8m 27s
Integration Tests (gateway idemix pkcs11 configtx configtxlator)	20m 29s
Integration Tests (sbe nwo msp)	9m 49s
	2h 30m 5s

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