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/session/src/lib.rs

@@ -114,7 +114,7 @@ mod mock;
 mod tests;
 pub mod weights;
 
-use codec::Decode;
+use codec::{Decode, MaxEncodedLen};
 use frame_support::{
 	decl_error, decl_event, decl_module, decl_storage,
 	dispatch::{self, DispatchError, DispatchResult},
@@ -367,7 +367,7 @@ pub trait Config: frame_system::Config {
 	type Event: From<Event> + Into<<Self as frame_system::Config>::Event>;
 
 	/// A stable ID for a validator.
-	type ValidatorId: Member + Parameter;
+	type ValidatorId: Member + Parameter + MaxEncodedLen;
 
 	/// A conversion from account ID to validator ID.
 	///