Elastic scaling: runtime dependency tracking and enactment (#3479)

Changes needed to implement the runtime part of elastic scaling:
https://github.com/paritytech/polkadot-sdk/issues/3131,
https://github.com/paritytech/polkadot-sdk/issues/3132,
https://github.com/paritytech/polkadot-sdk/issues/3202

Also fixes https://github.com/paritytech/polkadot-sdk/issues/3675

TODOs:

- [x] storage migration
- [x] optimise process_candidates from O(N^2)
- [x] drop backable candidates which form cycles
- [x] fix unit tests
- [x] add more unit tests
- [x] check the runtime APIs which use the pending availability storage.
We need to expose all of them, see
https://github.com/paritytech/polkadot-sdk/issues/3576
- [x] optimise the candidate selection. we're currently picking randomly
until we satisfy the weight limit. we need to be smart about not
breaking candidate chains while being fair to all paras -
https://github.com/paritytech/polkadot-sdk/pull/3573

Relies on the changes made in
https://github.com/paritytech/polkadot-sdk/pull/3233 in terms of the
inclusion policy and the candidate ordering

---------

Signed-off-by: alindima <alin@parity.io>
Co-authored-by: command-bot <>
Co-authored-by: eskimor <eskimor@users.noreply.github.com>

polkadot/runtime/parachains/src/paras_inherent/benchmarking.rs

@@ -145,10 +145,6 @@ benchmarks! {
 			assert_eq!(backing_validators.1.len(), votes);
 		}
 
-		assert_eq!(
-			inclusion::PendingAvailabilityCommitments::<T>::iter().count(),
-			cores_with_backed.len()
-		);
 		assert_eq!(
 			inclusion::PendingAvailability::<T>::iter().count(),
 			cores_with_backed.len()
@@ -209,10 +205,6 @@ benchmarks! {
 				);
 			}
 
-		assert_eq!(
-			inclusion::PendingAvailabilityCommitments::<T>::iter().count(),
-			cores_with_backed.len()
-		);
 		assert_eq!(
 			inclusion::PendingAvailability::<T>::iter().count(),
 			cores_with_backed.len()