[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/config.rs

@@ -4,7 +4,7 @@ use sensitive_url::SensitiveUrl;
 use serde_derive::{Deserialize, Serialize};
 use std::fs;
 use std::path::PathBuf;
-use types::{Graffiti, PublicKeyBytes};
+use types::{Address, Graffiti, Hash256, PublicKeyBytes, Uint256};
 
 /// Default directory name for the freezer database under the top-level data dir.
 const DEFAULT_FREEZER_DB_DIR: &str = "freezer_db";
@@ -74,6 +74,10 @@ pub struct Config {
     pub network: network::NetworkConfig,
     pub chain: beacon_chain::ChainConfig,
     pub eth1: eth1::Config,
+    pub execution_endpoints: Option<Vec<SensitiveUrl>>,
+    pub terminal_total_difficulty_override: Option<Uint256>,
+    pub terminal_block_hash: Option<Hash256>,
+    pub fee_recipient: Option<Address>,
     pub http_api: http_api::Config,
     pub http_metrics: http_metrics::Config,
     pub monitoring_api: Option<monitoring_api::Config>,
@@ -94,6 +98,10 @@ impl Default for Config {
             dummy_eth1_backend: false,
             sync_eth1_chain: false,
             eth1: <_>::default(),
+            execution_endpoints: None,
+            terminal_total_difficulty_override: None,
+            terminal_block_hash: None,
+            fee_recipient: None,
             disabled_forks: Vec::new(),
             graffiti: Graffiti::default(),
             http_api: <_>::default(),