imp(staking): format ConsensusPubkey into a base64 string

[luchenqun]

Description

This is the validator information returned through the rest interface http://127.0.0.1:1317/cosmos/staking/v1beta1/validators/evmosvaloper1hajh6rhhkjqkwet6wqld3lgx8ur4y3khljfx82

{
    "validator":{
        "operator_address":"evmosvaloper1hajh6rhhkjqkwet6wqld3lgx8ur4y3khljfx82",
        "consensus_pubkey":{
            "@type":"/cosmos.crypto.ed25519.PubKey",
            "key":"nfJ0axJC9dhta1MAE1EBFaVdxxkYzxYrBaHuJVjG//M="
        },
        .....
}

This is the validator information returned through the precompiled contract Staking interface function validator(string memory validatorAddress) external view returns (Validator calldata validator);

[
    "evmosvaloper1hajh6rhhkjqkwet6wqld3lgx8ur4y3khljfx82",
    "&Any{TypeUrl:/cosmos.crypto.ed25519.PubKey,Value:[10 32 157 242 116 107 18 66 245 216 109 107 83 0 19 81 1 21 165 93 199 25 24 207 22 43 5 161 238 37 88 198 255 243],XXX_unrecognized:[]}",
     .....
]

We see that the validator consensus_pubkey key information returns data formatted by bytes, which is not user friendly.

I formatted it, and after modification, the returned information is as follows, which is consistent with what is returned by the rest interface provided by cosmos.

[
    "evmosvaloper1hajh6rhhkjqkwet6wqld3lgx8ur4y3khljfx82",
    "nfJ0axJC9dhta1MAE1EBFaVdxxkYzxYrBaHuJVjG//M=",
     .....
]

[fedekunze]

A test is failing

[luchenqun]

A test is failing

done

[codecov]

Codecov Report

Merging #2046 (d07eb96) into main (8efa1e3) will increase coverage by 0.00%.
The diff coverage is 87.50%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2046   +/-   ##
=======================================
  Coverage   70.17%   70.17%           
=======================================
  Files         340      340           
  Lines       25446    25452    +6     
=======================================
+ Hits        17857    17862    +5     
- Misses       6672     6673    +1     
  Partials      917      917           

Files	Coverage Δ
precompiles/staking/types.go	74.88% <87.50%> (+0.11%)	⬆️

[CLAassistant]

All committers have signed the CLA.