Sort Validators like Tendermint in HistoricalInfo

[AdityaSripal]

Currently the order of ValidatorSet in staking.HistoricalInfo is not the same as order in tendermint. They should be the same in order to easily verify validatorset equality in IBC

[AdityaSripal]

Turns out we store sdk.Validators in HistoricalInfo rather than tmtypes.Validators, this is unfortunate because we can't use the tendermint sorting function as-is.

3 ways to move forward:

1. Implement a sort by power function in sdk and store sdk.Validators
2. Convert sdk.Validators to tendermint (easy), sort, and then reconvert to sdk (idk how to do this at first glance). It is also hacky
3. Change HistoricalInfo to store tendermint.ValidatorSet. This is the least hacky solution but requires the most changes.

Thoughts? @cwgoes @colin-axner @fedekunze

[fedekunze]

I would prefer 1)

[cwgoes]

Prefer (1) or (3). (1) is fine for now, the sort is simple enough.

[colin-axner]

I prefer 1), it would make SDK support for non-tendermint consensus easier to do in the future

[fedekunze]

Validators are also stored by power on the staking store under ValidatorsByPowerIndexKey. There's also an iterator function for bonded vals: IterateBondedValidatorsByPower which could be a good ref

[AdityaSripal]

Yup checking to see if that will match tendermints sorting now. I suspect not since it sorts by power than operator address

Wherease tendermint sorts by power than consensus address

[jackzampolin]

Related to this I was running into issues using stakingtypes.Validators.ToTMValidators to modify historical info.

Before fix
After fix