Add voter election with VRF

[zemyblue]

Add deleted voter elections in ostracon using VRF

@zemyblue @ulbqb All right. We have an implicit agreement in our private discussion about how to conduct voter elections, but this PR only contains bits and pieces of information, which is why I asked the question.

To state our conclusion for those interested in LINE Blockchain, we plan to move the behaviour known as voter election from ostracon to the lbm-sdk. This is because in Tendermint, the selection of Validators is the responsibility of the Cosmos-SDK and we have chosen to follow that approach. In this PR, we'll remove the voter election from Ostracon and implement it in a future update to the lbm-sdk.

Originally posted by @torao in https://github.com/line/ostracon/issues/543#issuecomment-1398185504