refactor: add Apply method to MemoryStore for transactional change sets #1736

Job	Run time
build-test-server-curl	7m 41s
contract-tests-curl	4m 25s
build-test-server-mac-curl	5m 36s
build-test-server-windows-curl	19m 12s
contract-tests	4m 10s
build-test-server	7m 38s
build-test-server-windows	17m 52s
build-test-server-mac	4m 24s
	1h 10m 58s

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