Generate storage info for pallet im_online

[georgesdib]

Fixes part of paritytech/polkadot-sdk#323

Refactor Im Online to use WeakBoundedVec instead of Vec, and generate storage info for that pallet.

polkadot companion: paritytech/polkadot#3744

@shawntabrizi @KiChjang @thiolliere

[gui1117]

apart from this last note, I think it should be good to me

[gui1117]

looks good to me, maybe name can be improved slightly

[KiChjang]

CI is complaining:

error[E0277]: the trait bound `frame_benchmarking::Vec<<T as pallet::Config>::AuthorityId>: EncodeLike<frame_support::WeakBoundedVec<<T as pallet::Config>::AuthorityId, <T as pallet::Config>::MaxKeys>>` is not satisfied
  --> frame/im-online/src/benchmarking.rs:49:17
   |
49 |     Keys::<T>::put(keys.clone());
   |                    ^^^^^^^^^^^^ the trait `EncodeLike<frame_support::WeakBoundedVec<<T as pallet::Config>::AuthorityId, <T as pallet::Config>::MaxKeys>>` is not implemented for `frame_benchmarking::Vec<<T as pallet::Config>::AuthorityId>`
   |
   = help: the following implementations were found:
             <frame_benchmarking::Vec<T> as EncodeLike<&[U]>>
             <frame_benchmarking::Vec<T> as EncodeLike<VecDeque<U>>>
             <frame_benchmarking::Vec<T> as EncodeLike<frame_benchmarking::Vec<U>>>
   = note: required by `frame_support::pallet_prelude::StorageValue::<Prefix, Value, QueryKind, OnEmpty>::put`

[georgesdib]

Rebased my branch to make it cleaner and force the checks of the polkadot companion

[gui1117]

bot merge

[ghost]

Waiting for commit status.

[ghost]

Merge failed: "Required status check "check-labels" is in progress."

[gui1117]

bot merge

[ghost]

Trying merge.