Fix clippy warnings (#1385)

## Issue Addressed

NA

## Proposed Changes

Fixes most clippy warnings and ignores the rest of them, see issue #1388.

beacon_node/beacon_chain/src/test_utils.rs

@@ -393,6 +393,7 @@ where
         (block_root.into(), new_state)
     }
 
+    #[allow(clippy::type_complexity)]
     /// `add_block()` repeated `num_blocks` times.
     pub fn add_blocks(
         &self,
@@ -422,6 +423,7 @@ where
         (blocks, states, slot, head_hash, state)
     }
 
+    #[allow(clippy::type_complexity)]
     /// A wrapper on `add_blocks()` to avoid passing enums explicitly.
     pub fn add_canonical_chain_blocks(
         &self,
@@ -446,6 +448,7 @@ where
         )
     }
 
+    #[allow(clippy::type_complexity)]
     /// A wrapper on `add_blocks()` to avoid passing enums explicitly.
     pub fn add_stray_blocks(
         &self,