Add braces to C++ single-line loops and conditionals (NFC) (#2973)

This makes code easier to read and more consistent between C++ and Java.
Also update clang-format settings to always add a line break (even if no braces are used).

wpilibcExamples/src/main/cpp/examples/GyroMecanum/cpp/Robot.cpp

@@ -56,5 +56,7 @@ class Robot : public frc::TimedRobot {
 };
 
 #ifndef RUNNING_FRC_TESTS
-int main() { return frc::StartRobot<Robot>(); }
+int main() {
+  return frc::StartRobot<Robot>();
+}
 #endif