[Merge] Implement execution_layer (#2635)

* Checkout serde_utils from rayonism

* Make eth1::http functions pub

* Add bones of execution_layer

* Modify decoding

* Expose Transaction, cargo fmt

* Add executePayload

* Add all minimal spec endpoints

* Start adding json rpc wrapper

* Finish custom JSON response handler

* Switch to new rpc sending method

* Add first test

* Fix camelCase

* Finish adding tests

* Begin threading execution layer into BeaconChain

* Fix clippy lints

* Fix clippy lints

* Thread execution layer into ClientBuilder

* Add CLI flags

* Add block processing methods to ExecutionLayer

* Add block_on to execution_layer

* Integrate execute_payload

* Add extra_data field

* Begin implementing payload handle

* Send consensus valid/invalid messages

* Fix minor type in task_executor

* Call forkchoiceUpdated

* Add search for TTD block

* Thread TTD into execution layer

* Allow producing block with execution payload

* Add LRU cache for execution blocks

* Remove duplicate 0x on ssz_types serialization

* Add tests for block getter methods

* Add basic block generator impl

* Add is_valid_terminal_block to EL

* Verify merge block in block_verification

* Partially implement --terminal-block-hash-override

* Add terminal_block_hash to ChainSpec

* Remove Option from terminal_block_hash in EL

* Revert merge changes to consensus/fork_choice

* Remove commented-out code

* Add bones for handling RPC methods on test server

* Add first ExecutionLayer tests

* Add testing for finding terminal block

* Prevent infinite loops

* Add insert_merge_block to block gen

* Add block gen test for pos blocks

* Start adding payloads to block gen

* Fix clippy lints

* Add execution payload to block gen

* Add execute_payload to block_gen

* Refactor block gen

* Add all routes to mock server

* Use Uint256 for base_fee_per_gas

* Add working execution chain build

* Remove unused var

* Revert "Use Uint256 for base_fee_per_gas"

This reverts commit 6c88f19ac4.

* Fix base_fee_for_gas Uint256

* Update execute payload handle

* Improve testing, fix bugs

* Fix default fee-recipient

* Fix fee-recipient address (again)

* Add check for terminal block, add comments, tidy

* Apply suggestions from code review

Co-authored-by: realbigsean <seananderson33@GMAIL.com>

* Fix is_none on handle Drop

* Remove commented-out tests

Co-authored-by: realbigsean <seananderson33@GMAIL.com>

beacon_node/client/src/builder.rs

@@ -16,6 +16,7 @@ use eth2::{
     types::{BlockId, StateId},
     BeaconNodeHttpClient, Error as ApiError, Timeouts,
 };
+use execution_layer::ExecutionLayer;
 use genesis::{interop_genesis_state, Eth1GenesisService};
 use lighthouse_network::NetworkGlobals;
 use monitoring_api::{MonitoringHttpClient, ProcessType};
@@ -146,6 +147,29 @@ where
             None
         };
 
+        let terminal_total_difficulty = config
+            .terminal_total_difficulty_override
+            .unwrap_or(spec.terminal_total_difficulty);
+        let terminal_block_hash = config
+            .terminal_block_hash
+            .unwrap_or(spec.terminal_block_hash);
+
+        let execution_layer = if let Some(execution_endpoints) = config.execution_endpoints {
+            let context = runtime_context.service_context("exec".into());
+            let execution_layer = ExecutionLayer::from_urls(
+                execution_endpoints,
+                terminal_total_difficulty,
+                terminal_block_hash,
+                config.fee_recipient,
+                context.executor.clone(),
+                context.log().clone(),
+            )
+            .map_err(|e| format!("unable to start execution layer endpoints: {:?}", e))?;
+            Some(execution_layer)
+        } else {
+            None
+        };
+
         let builder = BeaconChainBuilder::new(eth_spec_instance)
             .logger(context.log().clone())
             .store(store)
@@ -154,6 +178,7 @@ where
             .disabled_forks(disabled_forks)
             .graffiti(graffiti)
             .event_handler(event_handler)
+            .execution_layer(execution_layer)
             .monitor_validators(
                 config.validator_monitor_auto,
                 config.validator_monitor_pubkeys.clone(),