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/network/src/sync/block_lookups/mod.rs

@@ -40,7 +40,7 @@ mod single_block_lookup;
 #[cfg(test)]
 mod tests;
 
-pub type DownloadedBlock<T> = (Hash256, RpcBlock<T>);
+pub type DownloadedBlock<E> = (Hash256, RpcBlock<E>);
 
 const FAILED_CHAINS_CACHE_EXPIRY_SECONDS: u64 = 60;
 pub const SINGLE_BLOCK_LOOKUP_MAX_ATTEMPTS: u8 = 3;

beacon_node/network/src/sync/block_lookups/single_block_lookup.rs

@@ -319,13 +319,13 @@ impl<L: Lookup, T: BeaconChainTypes> SingleBlockLookup<L, T> {
 }
 
 /// The state of the blob request component of a `SingleBlockLookup`.
-pub struct BlobRequestState<L: Lookup, T: EthSpec> {
+pub struct BlobRequestState<L: Lookup, E: EthSpec> {
     /// The latest picture of which blobs still need to be requested. This includes information
     /// from both block/blobs downloaded in the network layer and any blocks/blobs that exist in
     /// the data availability checker.
     pub requested_ids: MissingBlobs,
     /// Where we store blobs until we receive the stream terminator.
-    pub blob_download_queue: FixedBlobSidecarList<T>,
+    pub blob_download_queue: FixedBlobSidecarList<E>,
     pub state: SingleLookupRequestState,
     _phantom: PhantomData<L>,
 }