Nest all namespaces

The compiler supports this now.  We can type less going forward.
No functional changes.

Signed-off-by: Stephan Pleines <pleines.stephan@gmail.com>
Change-Id: I29d6fa4f9aacc0e381f1a7637294db0392466995
diff --git a/y2022/control_loops/superstructure/collision_avoidance.cc b/y2022/control_loops/superstructure/collision_avoidance.cc
index 0c13295..33e4d6e 100644
--- a/y2022/control_loops/superstructure/collision_avoidance.cc
+++ b/y2022/control_loops/superstructure/collision_avoidance.cc
@@ -5,9 +5,7 @@
 #include "absl/functional/bind_front.h"
 #include "glog/logging.h"
 
-namespace y2022 {
-namespace control_loops {
-namespace superstructure {
+namespace y2022::control_loops::superstructure {
 
 CollisionAvoidance::CollisionAvoidance() {
   clear_min_intake_front_goal();
@@ -213,6 +211,4 @@
   }
 }
 
-}  // namespace superstructure
-}  // namespace control_loops
-}  // namespace y2022
+}  // namespace y2022::control_loops::superstructure