`zetanode` : implement `devnet`command for zetacore

[kingpinXD]

This would allow us to convert a testnet ot a mainnet node into a testing node with a separate chain id and validator set. We can then run tests on this node, and would have state data from the network without having to run any state export and import Link to the cosmos sdk implementation: https://github.com/cosmos/cosmos-sdk/blob/46c4d6ee2312fb24089b42185f5f092b31d9292b/server/start.go#L647

The core function for this is the testnetify function https://github.com/cosmos/cosmos-sdk/blob/46c4d6ee2312fb24089b42185f5f092b31d9292b/server/start.go#L733 Which updates the genesis file and the state to convert it into a separate network.

[lumtis]

Context why we need this functionality?

[kingpinXD]

This can be used to run tests on a node that has all the testnet/mainnet state. It would enable us to replace the state export tests. (Which are currently blocked becuase the genesis export is too big )