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/aos/network/team_number.cc b/aos/network/team_number.cc
index 8885b52..28ee67a 100644
--- a/aos/network/team_number.cc
+++ b/aos/network/team_number.cc
@@ -13,8 +13,7 @@
     "If set, this forces the hostname of this node to be the provided "
     "hostname.");
 
-namespace aos {
-namespace network {
+namespace aos::network {
 namespace team_number_internal {
 
 std::optional<uint16_t> ParseRoborioTeamNumber(
@@ -150,5 +149,4 @@
   return number;
 }
 
-}  // namespace network
-}  // namespace aos
+}  // namespace aos::network