Rust

Add zk-nullifier example and reorganize zk/ folder #139

Job	Run time
airdrop-implementations/simple-claim/program	5m 26s
zk/zk-merkle-proof	2m 25s
basic-operations/native/native-program-reinit	1m 13s
zk/zk-id	6m 30s
counter/pinocchio	5m 29s
account-comparison	1m 16s
basic-operations/native/native-program-burn	1m 20s
basic-operations/native/native-program-update	1m 16s
create-and-update	1m 38s
basic-operations/native/native-program-create	1m 15s
counter/native	1m 19s
zk/zk-nullifier	6m 9s
basic-operations/native/native-program-close	1m 24s
	36m 40s

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