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_bot3/constants.cc b/y2022_bot3/constants.cc
index ef5ad32..8defbc6 100644
--- a/y2022_bot3/constants.cc
+++ b/y2022_bot3/constants.cc
@@ -16,8 +16,7 @@
 #include "y2022_bot3/control_loops/superstructure/climber/integral_climber_plant.h"
 #include "y2022_bot3/control_loops/superstructure/intake/integral_intake_plant.h"
 
-namespace y2022_bot3 {
-namespace constants {
+namespace y2022_bot3::constants {
 
 const int Values::kZeroingSampleSize;
 
@@ -143,5 +142,4 @@
 
 Values MakeValues() { return MakeValues(aos::network::GetTeamNumber()); }
 
-}  // namespace constants
-}  // namespace y2022_bot3
+}  // namespace y2022_bot3::constants