add support GetMultipleKeys #3973

Job	Run time
Basic Checks	1m 46s
Unit Tests	11m 17s
Integration Tests (raft)	14m 13s
Integration Tests (pvtdata)	14m 21s
Integration Tests (pvtdatapurge e2e)	22m 21s
Integration Tests (ledger)	15m 47s
Integration Tests (lifecycle)	7m 47s
Integration Tests (smartbft)	22m 1s
Integration Tests (discovery gossip devmode pluggable)	10m 43s
Integration Tests (gateway idemix pkcs11 configtx configtxlator)	16m 26s
Integration Tests (sbe nwo msp)	9m 41s
	2h 26m 23s

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