Add test coverage of evmstaking module

[zsystm]

Coverage status

File	Cov(%)	PR	Cov after PR(%)
evmstaking/keeper/abci.go	0.0	#79	84.5%
evmstaking/keeper/deposit.go	0.0	#71	94.4%
evmstaking/keeper/genesis.go	0.0	#111	71.4%
evmstaking/keeper/grpc_query.go	0.0	#164	78.9%
evmstaking/keeper/keeper.go	11.4	#75	94.3%
evmstaking/keeper/msg_server.go	0.0	#70	95.5%
evmstaking/keeper/params.go	0.0	#102	70%
evmstaking/keeper/redelegation.go	72.4	#77	100%
evmstaking/keeper/set_address.go	0.0	#67	87.5%
evmstaking/keeper/staking_queue.go	0.0	#68	84.6%
evmstaking/keeper/unjail.go	0.0	#104	100%
evmstaking/keeper/utils.go	100.0	#76	100%
evmstaking/keeper/validator.go	0.0	#66	86.0%
evmstaking/keeper/withdraw.go	0.0	#65	86.8%
evmstaking/keeper/withdrawal_queue.go	0.0	#61	78.8%
evmstaking/types/genesis.go	0.0	#112	100%
evmstaking/types/params.go	0.0	#103	100%
evmstaking/types/staking_contract.go	75.0	#56	100%
evmstaking/types/withdraw.go	0.0	#55	100%

• auto generated files like *pb.go or *mocks.go are not target
• status will be updated whenever related PR or work is done