Add set_council_parameters root dispatchable #238
Description
Dispatchable called by Set Council Parameters Proposal to be able to update all parameters which can currently be set using existing set_param_* :
AnnouncingPeriod
VotingPeriod
RevealingPeriod
MinCouncilStake
NewTermDuration
CouncilSize
CandidacyLimit
MinVotingStake
noting that all parameters only have an effect for the next election round