Governance controlled accounts

# Description
A specific account (such as the faucet server address: https://joystream.subscan.io/account/j4WJyNrJz5RA5ZvGarCcrqfAfAw8cxqK1qFP8T46TAskf8ajS) that cannot be owned by an individual, but rather the DAO can assign use of the account to a specific actor (such as a WG lead). This would enable the account to have a longstanding address and remove some complications with "necessary accounts" (such as for faucet servers, upload servers and some other uses) so that new accounts do not have to be created/handled if a lead changes.
* The private key/seed for these accounts would never be revealed or accessible and only the runtime effectively has access to it. What this means is that a lead _could_ abuse the account privileges but the lead could be changed afterwards and there is no security risk associated with keeping use of the same account.
* Ideally, each WG lead would get at least one of these accounts across the DAO
* The Council itself may also want an account

# Use cases
It is difficult to imagine the possible use cases for such a feature, so at least some examples are going to be outlined below. This is by no means exhaustive
* YT-sync collaborator server/account
* Faucet server/account
* Curator WG could own a membership + buy NFTs on behalf of the DAO

# Related issues
* https://github.com/Joystream/joystream/issues/2870