Add private voting features

[kopeboy]

I think it would be very nice to have "private" voting, which actually can be implemented in different ways, and with the most simple I mean private only before the vote ends (eliminating influences).

We could copy from the commit-reveal scheme used by Zeitgeist (a Polkadot parachain): they use it for Jurors' vote on Court cases (appeals on their prediction markets): https://docs.zeitgeist.pm/docs/learn/court
I haven't searched for the code on their Github yet, but the feature is going to be tested on mainnet for the first time on May 11th 2024 (so you could check the events on Subscan.io): https://app.zeitgeist.pm/court

[JakeHartnell]

We probably want to implment something like MACI: https://maci.pse.dev/

Dora Factory has a basic CosmWasm implementation: https://github.com/DoraFactory/cosmwasm-maci