Fix clippy warnings (#1385)

## Issue Addressed

NA

## Proposed Changes

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

consensus/proto_array/src/bin.rs

@@ -1,5 +1,4 @@
 use proto_array::fork_choice_test_definition::*;
-use serde_yaml;
 use std::fs::File;
 
 fn main() {

consensus/proto_array/src/proto_array.rs

@@ -358,14 +358,12 @@ impl ProtoArray {
                         }
                     }
                 }
+            } else if child_leads_to_viable_head {
+                // There is no current best-child and the child is viable.
+                change_to_child
             } else {
-                if child_leads_to_viable_head {
-                    // There is no current best-child and the child is viable.
-                    change_to_child
-                } else {
-                    // There is no current best-child but the child is not viable.
-                    no_change
-                }
+                // There is no current best-child but the child is not viable.
+                no_change
             };
 
         let parent = self

consensus/proto_array/src/proto_array_fork_choice.rs

@@ -95,7 +95,7 @@ impl ProtoArrayForkChoice {
             .map_err(|e| format!("Failed to add finalized block to proto_array: {:?}", e))?;
 
         Ok(Self {
-            proto_array: proto_array,
+            proto_array,
             votes: ElasticList::default(),
             balances: vec![],
         })
@@ -171,6 +171,10 @@ impl ProtoArrayForkChoice {
         self.proto_array.nodes.len()
     }
 
+    pub fn is_empty(&self) -> bool {
+        self.proto_array.nodes.is_empty()
+    }
+
     pub fn contains_block(&self, block_root: &Hash256) -> bool {
         self.proto_array.indices.contains_key(block_root)
     }

consensus/proto_array/src/ssz_container.rs

@@ -45,7 +45,7 @@ impl From<SszContainer> for ProtoArrayForkChoice {
         };
 
         Self {
-            proto_array: proto_array,
+            proto_array,
             votes: ElasticList(from.votes),
             balances: from.balances,
         }