Unify components for Polkadot bridges

[bkontur]

Description

At least P/K and Snowbridge shares some commonalities (xcm routing, congestion, dynamic fees, collecting rewards, ...) which are unnecessary implemented twice.

• one common pallet for relayers and rewards - see comment Make pallet-bridge-rewards generic over RewardKind #7492
  • store rewards/claims as xcm::Assets
  • generalize reward/claim identifier to support both P/K and Snowfork bridge
  • Relayer rewards paid to specified location account #6578
  • Use sovereign accounts of sending chains to pay relayer rewards parity-bridges-common#2585
• use pallet-xcm-bridge-hub-router for Snowbridge (dynamic fees, congestion)
• use subscribe/syncing proof from BH to AH for Snowbridge - Investigation of deploying pallet-bridge-messages on the source/destination chain (without finality pallets) a.k.a. sync finality proofs service #5827
• investigate to use pallet-message-queue for P/K bridge instead custom one

Trait changes:

• ExporterFor change Option<Asset> to Assets or Option<Assets to support more fees and be aligned with SendXcm trait
• ExportXcm - remove channel and change the order or params:

  fn validate(
   	universal_source: &mut Option<InteriorLocation>,
   	network: NetworkId,
   	destination: &mut Option<InteriorLocation>,
   	message: &mut Option<Xcm<()>>,
  ) -> SendResult<Self::Ticket>;