common/vector_math: Move Vec[x] types into the Common namespace

These types are within the common library, so they should be using the
Common namespace.

src/input_common/udp/client.h

@@ -31,7 +31,7 @@ struct Version;
 
 struct DeviceStatus {
     std::mutex update_mutex;
-    std::tuple<Math::Vec3<float>, Math::Vec3<float>> motion_status;
+    std::tuple<Common::Vec3<float>, Common::Vec3<float>> motion_status;
     std::tuple<float, float, bool> touch_status;
 
     // calibration data for scaling the device's touch area to 3ds