Use E for EthSpec globally (#5264)

* Use `E` for `EthSpec` globally

* Fix tests

* Merge branch 'unstable' into e-ethspec

* Merge branch 'unstable' into e-ethspec

# Conflicts:
#	beacon_node/execution_layer/src/engine_api.rs
#	beacon_node/execution_layer/src/engine_api/http.rs
#	beacon_node/execution_layer/src/engine_api/json_structures.rs
#	beacon_node/execution_layer/src/test_utils/handle_rpc.rs
#	beacon_node/store/src/partial_beacon_state.rs
#	consensus/types/src/beacon_block.rs
#	consensus/types/src/beacon_block_body.rs
#	consensus/types/src/beacon_state.rs
#	consensus/types/src/config_and_preset.rs
#	consensus/types/src/execution_payload.rs
#	consensus/types/src/execution_payload_header.rs
#	consensus/types/src/light_client_optimistic_update.rs
#	consensus/types/src/payload.rs
#	lcli/src/parse_ssz.rs

beacon_node/execution_layer/src/test_utils/mod.rs

@@ -84,14 +84,14 @@ impl Default for MockExecutionConfig {
     }
 }
 
-pub struct MockServer<T: EthSpec> {
+pub struct MockServer<E: EthSpec> {
     _shutdown_tx: oneshot::Sender<()>,
     listen_socket_addr: SocketAddr,
     last_echo_request: Arc<RwLock<Option<Bytes>>>,
-    pub ctx: Arc<Context<T>>,
+    pub ctx: Arc<Context<E>>,
 }
 
-impl<T: EthSpec> MockServer<T> {
+impl<E: EthSpec> MockServer<E> {
     pub fn unit_testing() -> Self {
         Self::new(
             &runtime::Handle::current(),
@@ -133,7 +133,7 @@ impl<T: EthSpec> MockServer<T> {
             kzg,
         );
 
-        let ctx: Arc<Context<T>> = Arc::new(Context {
+        let ctx: Arc<Context<E>> = Arc::new(Context {
             config: server_config,
             jwt_key,
             log: null_logger().unwrap(),
@@ -211,7 +211,7 @@ impl<T: EthSpec> MockServer<T> {
         )
     }
 
-    pub fn execution_block_generator(&self) -> RwLockWriteGuard<'_, ExecutionBlockGenerator<T>> {
+    pub fn execution_block_generator(&self) -> RwLockWriteGuard<'_, ExecutionBlockGenerator<E>> {
         self.ctx.execution_block_generator.write()
     }
 
@@ -423,7 +423,7 @@ impl<T: EthSpec> MockServer<T> {
             .insert_block_without_checks(block);
     }
 
-    pub fn get_block(&self, block_hash: ExecutionBlockHash) -> Option<Block<T>> {
+    pub fn get_block(&self, block_hash: ExecutionBlockHash) -> Option<Block<E>> {
         self.ctx
             .execution_block_generator
             .read()
@@ -501,12 +501,12 @@ impl warp::reject::Reject for AuthError {}
 /// A wrapper around all the items required to spawn the HTTP server.
 ///
 /// The server will gracefully handle the case where any fields are `None`.
-pub struct Context<T: EthSpec> {
+pub struct Context<E: EthSpec> {
     pub config: Config,
     pub jwt_key: JwtKey,
     pub log: Logger,
     pub last_echo_request: Arc<RwLock<Option<Bytes>>>,
-    pub execution_block_generator: RwLock<ExecutionBlockGenerator<T>>,
+    pub execution_block_generator: RwLock<ExecutionBlockGenerator<E>>,
     pub preloaded_responses: Arc<Mutex<Vec<serde_json::Value>>>,
     pub previous_request: Arc<Mutex<Option<serde_json::Value>>>,
     pub static_new_payload_response: Arc<Mutex<Option<StaticNewPayloadResponse>>>,
@@ -525,10 +525,10 @@ pub struct Context<T: EthSpec> {
     pub syncing_response: Arc<Mutex<Result<bool, String>>>,
 
     pub engine_capabilities: Arc<RwLock<EngineCapabilities>>,
-    pub _phantom: PhantomData<T>,
+    pub _phantom: PhantomData<E>,
 }
 
-impl<T: EthSpec> Context<T> {
+impl<E: EthSpec> Context<E> {
     pub fn get_new_payload_status(
         &self,
         block_hash: &ExecutionBlockHash,
@@ -637,8 +637,8 @@ async fn handle_rejection(err: Rejection) -> Result<impl warp::Reply, Infallible
 ///
 /// Returns an error if the server is unable to bind or there is another error during
 /// configuration.
-pub fn serve<T: EthSpec>(
-    ctx: Arc<Context<T>>,
+pub fn serve<E: EthSpec>(
+    ctx: Arc<Context<E>>,
     shutdown: impl Future<Output = ()> + Send + Sync + 'static,
 ) -> Result<(SocketAddr, impl Future<Output = ()>), Error> {
     let config = &ctx.config;
@@ -653,7 +653,7 @@ pub fn serve<T: EthSpec>(
     let root = warp::path::end()
         .and(warp::body::json())
         .and(ctx_filter.clone())
-        .and_then(|body: serde_json::Value, ctx: Arc<Context<T>>| async move {
+        .and_then(|body: serde_json::Value, ctx: Arc<Context<E>>| async move {
             let id = body
                 .get("id")
                 .and_then(serde_json::Value::as_u64)
@@ -700,7 +700,7 @@ pub fn serve<T: EthSpec>(
     let echo = warp::path("echo")
         .and(warp::body::bytes())
         .and(ctx_filter)
-        .and_then(|bytes: Bytes, ctx: Arc<Context<T>>| async move {
+        .and_then(|bytes: Bytes, ctx: Arc<Context<E>>| async move {
             *ctx.last_echo_request.write() = Some(bytes.clone());
             Ok::<_, warp::reject::Rejection>(
                 warp::http::Response::builder().status(200).body(bytes),