Migrate to Governance v2 primitives

[ghzlatarev]

There are a couple of new pallets pallet_conviction_voting and pallet_referenda, which provide an alternative governance model paritytech/substrate#10195

The major difference is that you define a number of "referenda tracks" in your runtime, each with different attributes like who to dispatch the call if it passed, the voting period, thresholds, etc.
Anyone can propose a referendum at any time for any reason in these tracks. If it reaches the predetermined requirements it is passed, otherwise fails.

The main point is to increase decentralization. On one hand this removes centralization around the Council. Furthermore it removes the 1 public proposal per 2 periods limit, hopefully boosting participation.