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/y2024_defense/constants.cc b/y2024_defense/constants.cc
index fa7a14c..31b3ae3 100644
--- a/y2024_defense/constants.cc
+++ b/y2024_defense/constants.cc
@@ -13,8 +13,7 @@
 #include "aos/mutex/mutex.h"
 #include "aos/network/team_number.h"
 
-namespace y2024_defense {
-namespace constants {
+namespace y2024_defense::constants {
 
 Values MakeValues(uint16_t team) {
   LOG(INFO) << "creating a Constants for team: " << team;
@@ -26,5 +25,4 @@
 
 Values MakeValues() { return MakeValues(aos::network::GetTeamNumber()); }
 
-}  // namespace constants
-}  // namespace y2024_defense
+}  // namespace y2024_defense::constants