Add poll/survey feature

[Noc2]

As mentioned in the kusama directory, I think adding a poll feature would be nice (especially for treasury proposals). This way you can get some feedback/share your ideas, before you risk losing your tokens on-chain. I think it might even be useful to make this mandatory for treasury proposals, but that’s up to the council.

Similar existing solutions:
https://vote.makerdao.com/polling
https://proposals.decred.org (called discussion)

During this poll/survey it might be useful to highlight the opinion of council members (in case they participate in the poll).

[siman]

We are going to implement a specific type of post: on-chain poll.
I think it makes sense to support 2 types of polls:

1. Single choice
2. Multi-choice

[subsocialdev]

Check out this:
https://github.com/MVPWorkshop/substrate-quadratic-democracy