Restructure cached tree hash files, breaks tests

eth2/utils/ssz/src/cached_tree_hash/impls.rs

@@ -0,0 +1,30 @@
+use super::*;
+use crate::ssz_encode;
+
+impl CachedTreeHash for u64 {
+    fn build_cache_bytes(&self) -> Vec<u8> {
+        merkleize(ssz_encode(self))
+    }
+
+    fn num_bytes(&self) -> usize {
+        8
+    }
+
+    fn max_num_leaves(&self) -> usize {
+        1
+    }
+
+    fn cached_hash_tree_root(
+        &self,
+        other: &Self,
+        cache: &mut TreeHashCache,
+        chunk: usize,
+    ) -> Option<usize> {
+        if self != other {
+            let leaf = merkleize(ssz_encode(self));
+            cache.modify_chunk(chunk, &leaf)?;
+        }
+
+        Some(chunk + 1)
+    }
+}