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/lighthouse_network/src/service/behaviour.rs

@@ -16,19 +16,19 @@ pub type SubscriptionFilter =
 pub type Gossipsub = gossipsub::Behaviour<SnappyTransform, SubscriptionFilter>;
 
 #[derive(NetworkBehaviour)]
-pub(crate) struct Behaviour<AppReqId, TSpec>
+pub(crate) struct Behaviour<AppReqId, E>
 where
     AppReqId: ReqId,
-    TSpec: EthSpec,
+    E: EthSpec,
 {
     /// Keep track of active and pending connections to enforce hard limits.
     pub connection_limits: libp2p::connection_limits::Behaviour,
     /// The peer manager that keeps track of peer's reputation and status.
-    pub peer_manager: PeerManager<TSpec>,
+    pub peer_manager: PeerManager<E>,
     /// The Eth2 RPC specified in the wire-0 protocol.
-    pub eth2_rpc: RPC<RequestId<AppReqId>, TSpec>,
+    pub eth2_rpc: RPC<RequestId<AppReqId>, E>,
     /// Discv5 Discovery protocol.
-    pub discovery: Discovery<TSpec>,
+    pub discovery: Discovery<E>,
     /// Keep regular connection to peers and disconnect if absent.
     // NOTE: The id protocol is used for initial interop. This will be removed by mainnet.
     /// Provides IP addresses and peer information.