update version of substrate dependencies to polkadot v0940

[b-yap]

partially closes pendulum issue 219

General overview of the changes:

1. rename grandpa traits
2. rename random-collective-flip crates
3. conversion of <T as frame_system::Config>::Origin::from(RawOrigin::Root) to a shorter: RawOrigin::Root.into() in benchmarking.rs
4. generate new weights for all extrinsics
5. update implementation of pallet_grandpa in runtime
6. added the toolchain so it's consistent with spacewalk

[TorstenStueber]

Thanks for upgrading this whole repository. It is unfortunate that together with the pallet we have a whole runtime and node here, although we only need the pallet. This makes upgrading to a new Polkadot version much harder.

We should consider to change this in the future.

[ebma]

It's really great that you got the benchmarking working again but we have to be careful with the values as I think we changed few of them manually (as the benchmarks were broken at the time). Let's maybe remove the weight generation from this PR again as you suggested @b-yap.

[ebma]

The rest looks good to me