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

consensus/state_processing/src/common/altair.rs

@@ -24,8 +24,8 @@ impl BaseRewardPerIncrement {
 /// shown to be a significant optimisation.
 ///
 /// Spec v1.1.0
-pub fn get_base_reward<T: EthSpec>(
-    state: &BeaconState<T>,
+pub fn get_base_reward<E: EthSpec>(
+    state: &BeaconState<E>,
     index: usize,
     base_reward_per_increment: BaseRewardPerIncrement,
     spec: &ChainSpec,