statement-distribution: fix filtering of statements for elastic parachains (#3879)

fixes https://github.com/paritytech/polkadot-sdk/issues/3775

Additionally moves the claim queue fetch utilities into
`subsystem-util`.

TODO:
- [x] fix tests
- [x] add elastic scaling tests

---------

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

polkadot/node/network/statement-distribution/src/error.rs

@@ -81,6 +81,9 @@ pub enum Error {
 	#[error("Fetching validator groups failed {0:?}")]
 	FetchValidatorGroups(RuntimeApiError),
 
+	#[error("Fetching claim queue failed {0:?}")]
+	FetchClaimQueue(runtime::Error),
+
 	#[error("Attempted to share statement when not a validator or not assigned")]
 	InvalidShare,