Refactor staking precompile to use getCosmosAddress()

[fbac]

          probably can be used from other precompiles since it is generic and i think can be used in staking precompile as well

Originally posted by @skosito in https://github.com/zeta-chain/node/pull/2860#discussion_r1763099149

[kingpinXD]

Might be a good idea to add a GitHub code link to the function