[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 6c88f19ac45db834dd4dbf7a3c6e7242c1c0f735.

* 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/eth1/src/http.rs

@@ -479,7 +479,7 @@ pub async fn send_rpc_request(
 }
 
 /// Accepts an entire HTTP body (as a string) and returns either the `result` field or the `error['message']` field, as a serde `Value`.
-fn response_result_or_error(response: &str) -> Result<Value, RpcError> {
+pub fn response_result_or_error(response: &str) -> Result<Value, RpcError> {
     let json = serde_json::from_str::<Value>(response)
         .map_err(|e| RpcError::InvalidJson(e.to_string()))?;
 
@@ -501,7 +501,7 @@ fn response_result_or_error(response: &str) -> Result<Value, RpcError> {
 /// Therefore, this function is only useful for numbers encoded by the JSON RPC.
 ///
 /// E.g., `0x01 == 1`
-fn hex_to_u64_be(hex: &str) -> Result<u64, String> {
+pub fn hex_to_u64_be(hex: &str) -> Result<u64, String> {
     u64::from_str_radix(strip_prefix(hex)?, 16)
         .map_err(|e| format!("Failed to parse hex as u64: {:?}", e))
 }