add historical summaries (#3865)

* add historical summaries

* fix tree hash caching, disable the sanity slots test with fake crypto

* add ssz static HistoricalSummary

* only store historical summaries after capella

* Teach `UpdatePattern` about Capella

* Tidy EF tests

* Clippy

Co-authored-by: Michael Sproul <michael@sigmaprime.io>

consensus/state_processing/src/per_epoch_processing/capella/historical_summaries_update.rs

@@ -0,0 +1,23 @@
+use crate::EpochProcessingError;
+use safe_arith::SafeArith;
+use types::historical_summary::HistoricalSummary;
+use types::{BeaconState, EthSpec};
+
+pub fn process_historical_summaries_update<T: EthSpec>(
+    state: &mut BeaconState<T>,
+) -> Result<(), EpochProcessingError> {
+    // Set historical block root accumulator.
+    let next_epoch = state.next_epoch()?;
+    if next_epoch
+        .as_u64()
+        .safe_rem((T::slots_per_historical_root() as u64).safe_div(T::slots_per_epoch())?)?
+        == 0
+    {
+        let summary = HistoricalSummary::new(state);
+        return state
+            .historical_summaries_mut()?
+            .push(summary)
+            .map_err(Into::into);
+    }
+    Ok(())
+}