Clippy clean (#536)

* Change into_iter to iter

* Fix clippy 'easy' warnings

* Clippy eth2/utils

* Add struct NetworkInfo

* Clippy for types, utils, and beacon_node/store/src/iters.rs

* Cargo fmt

* Change foo to my_foo

* Remove complex signature

* suppress clippy warning for unit_value in benches

* Use enumerate instead of iterating over range

* Allow trivially_copy_pass_by_ref in serde_utils

eth2/utils/lighthouse_metrics/src/lib.rs

@@ -100,7 +100,9 @@ pub fn start_timer(histogram: &Result<Histogram>) -> Option<HistogramTimer> {
 
 /// Stops a timer created with `start_timer(..)`.
 pub fn stop_timer(timer: Option<HistogramTimer>) {
-    timer.map(|t| t.observe_duration());
+    if let Some(t) = timer {
+        t.observe_duration()
+    }
 }
 
 pub fn inc_counter(counter: &Result<IntCounter>) {