implement 'preferendums' in kreivo governance templates

[monsieurbulb]

implement statedtech's preferendum system and pallet in krievo to enable root proposal/initiatives.

Root is a common good initiative which aims to tackle current issues with on-chain governance - low voter participation, lack of oversight and siloed knowledge, through a fun, collaborative and educational process that plants composable proposals (preferendums) that are nurtured by network contributors to grow decentralised teams from the ground up.

We want to realise the potential of on-chain governance by enabling proposals and teams to be created, iterated and formed through our protocol that interacts directly on-chain, showing the power of "console-like" queries to CRUD proposals from IPFS directly to the blockchain.

Background https://forum.polkadot.network/t/a-better-treasury-system/291/18

[olanod]

Related to this, we are exploring adding the feature to pallet referenda to be able to edit a preimage during the prepare period and allow proposers to use that time for discussion/feedback, based on that the proposal can be updated without having to open a new referendum.