* Decouple the PoA bridge code from Rialto
* Remove Rialto PoA bridge code
* Remove relays/bin-ethereum code
* Remove relays/client-ethereum code
* Remove modules/ethereum code
* Remove modules/ethereum-contract-builtin code
* Remove PoA bridge documentation
* Remove primitives/ethereum-poa code
* Decouple Rialto from currency-exchange
* Fix building with runtime-benchmarks
* Fix should_encode_bridge_send_message_call test
    Because we removed some runtime modules/pallets, the
    substrate2substrate bridge pallet has a different index within
    the runtime so its calls have a different encoding.
    Update the test to use the new encoding.
* Update readme - no more PoA bridge
* Remove deployments/bridges/poa-rialto
    Also removes:
    - deployments/networks/eth-poa.yml
    - deployments/networks/OpenEthereum.Dockerfile
* Remove deployments/dev/poa-config
* Update deployments readme - no more PoA bridge
* Remove eth-related scripts
    Deletes:
    - deployments/networks/eth-poa.yml
    - scripts/run-openethereum-node.sh
* Remove poa-relay from gitlab-ci
* Dockerfiles to use substrate-relay as default
* Remove modules/currency-exchange code
* Remove primitives/currency-exchange code

Signed-off-by: acatangiu <adrian@parity.io>

* Decouple `relays/client-substrate` from `headers_relay`
* Remove `blocks_in_state` from `SyncLoopMetrics`
    This metric was only relevant for PoA <> Substrate bridge.
* Move `sync_loop_metrics.rs` to `relays/finality`
* Remove unused `SyncLoopMetrics::update()`
* Hook up SyncLoopMetrics to finality_loop
* Delete now unused `relays/headers`

Signed-off-by: acatangiu <adrian@parity.io>

* unify metric names

* refactor standalone metrics

* headers sync metrics

* post-merge fix

* fix compilation

* fmt

* fix dashboards

* fix local dashboards

* update Rococo/Wococo runtime version

* remove commented code

* fixed grumbles

* fmt

* fixed widget names

* Add Beefy pallet to Rialto runtime

* Add Beefy gadget to Rialto node

* Add MMR pallet to Rialto runtime

* Add Beefy pallet to Millau runtime

* Add Beefy gadget to Millau node

* Add MMR pallet to Millau runtime

* Add pallet_beefy_mmr to Millau runtime

* Add pallet_beefy_mmr to Rialto runtime

* Implement MMR and BEEFY APIs in Rialto

* fix unit tests

- should_encode_bridge_send_message_call() tests for new
  runtime encoding resulted from newly added pallets.
- runtime size_of::<Call>() slightly increased from newly
  added pallets.

* fix grumbles

* tighten clippy allowances

* fix more grumbles

* Add MMR RPC to Rialto and Millau nodes

Also implement MmrApi in Millau runtime.

* rialto: use upstream polkadot_client::RuntimeApiCollection

* fixed storage_parameter_key

* added test for storage_parameter_key

Signed-off-by: Adrian Catangiu <adrian@parity.io>