* Split `reconnect_failed_client()` logic

* Reorganize block checking logic as state machine

This way we'll be able to save the state in case of a failure

* Impl SubstrateEquivocationDetectionPipeline for Millau

* Impl SubstrateEquivocationDetectionPipeline for Rialto

* Make BridgeHubSignedExtension more generic

* Define generate_report_equivocation_call_builder!() macro

* Impl SubstrateEquivocationDetectionPipeline for Rococo

* Impl SubstrateEquivocationDetectionPipeline for Wococo

* Impl SubstrateEquivocationDetectionPipeline for Kusama

* Impl SubstrateEquivocationDetectionPipeline for Polkadot

* Complex relayer simplification

- remove `signer` and `transactions_mortality` and add `tx_params`
- change the order of some fields

* Add equivocation detection CLI traits

* Complex relayer: start equivocation detectin loop

* Update runtimes regeneration script

* Equivocation loop: Fix infinite loop

* Revert "Complex relayer: start equivocation detectin loop"

This reverts commit b518ef85.

* Add subcommand for starting the equivocation detection loop

* Fixes

* Initialize empty metrics for the equivocations detector loop

* Implement basic equivocations detection loop (#2367)

* FinalityProofsBuf adjustments

- store a Vec<FinalityProof>
- transform prune `buf_limit` to Option

* FinalityProof: add target_header_hash()

* Target client: implement best_synced_header_hash()

* Implement first version of the equivocations detection loop

* Address code review comments

* Leftover

* polkadot-staging adjustments

* Split FinalitySyncPipeline and SourceClient

* Move some logic to finality_base

* Add empty equivocation detection clients

* Add equivocation reporting logic to the source client

* Use convenience trait for SubstrateFinalitySyncPipeline

* Define JustificationVerificationContext for GRANDPA

* Equivocation source client: finality_verification_context()

* Equivocation source client: synced_headers_finality_info()

* reuse HeaderFinalityInfo

* Define EquivocationsFinder

* Fix spellcheck

* Address review comments

* Avoid equivocations lookup errors