Generate storage info for pallet im_online (#9654)

* Integrating WrapperOpaque from PR #9738

* Adding storage_info to pallet im-online
Changing some `Vec` to `WeakBoundedVec`
Adding the following bounds:
* `MaxKeys
* `MaxPeerInHeartbeats`
* `MaxPeerDataEncodingSize`
to limit the size of `WeakBoundedVec`

* Fix syntax

* Need to clone keys

* Changes in formatting

substrate/frame/support/src/traits/validation.rs

@@ -18,7 +18,7 @@
 //! Traits for dealing with validation and validators.
 
 use crate::{dispatch::Parameter, weights::Weight};
-use codec::{Codec, Decode};
+use codec::{Codec, Decode, MaxEncodedLen};
 use sp_runtime::{
 	traits::{Convert, Zero},
 	BoundToRuntimeAppPublic, ConsensusEngineId, Permill, RuntimeAppPublic,
@@ -31,7 +31,7 @@ use sp_std::prelude::*;
 /// Something that can give information about the current validator set.
 pub trait ValidatorSet<AccountId> {
 	/// Type for representing validator id in a session.
-	type ValidatorId: Parameter;
+	type ValidatorId: Parameter + MaxEncodedLen;
 	/// A type for converting `AccountId` to `ValidatorId`.
 	type ValidatorIdOf: Convert<AccountId, Option<Self::ValidatorId>>;