Actor validation redundant

@shamil-gadelshin
Aren't these lines redundant? I think they're validating twice
https://github.com/Joystream/joystream/blob/1c37a713511cfaf35b9577069f78827492324f2c/runtime-modules/bounty/src/lib.rs#L784
https://github.com/Joystream/joystream/blob/1c37a713511cfaf35b9577069f78827492324f2c/runtime-modules/bounty/src/lib.rs#L1135
We could change these extrinsics by removing creator and oracle inputs, since we already have that information in the chain and we already do the necessary validation with ensure_bounty_exists
Something like this

        pub fn cancel_bounty(origin, bounty_id: T::BountyId) {

            let bounty = Self::ensure_bounty_exists(&bounty_id)?;
            BountyActorManager::<T>::ensure_bounty_actor_manager(
                origin,
                bounty.creation_params.creator.clone(),
            )?;
            ...
       }


        pub fn submit_oracle_judgment(
            origin,
            bounty_id: T::BountyId,
            judgment: OracleJudgment<T::EntryId, BalanceOf<T>>
        ) {
            let bounty = Self::ensure_bounty_exists(&bounty_id)?;
            BountyActorManager::<T>::ensure_bounty_actor_manager(
                origin,
                bounty.creation_params.oracle.clone(),
            )?;
            ...
      }