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).

glass/src/lib/native/cpp/hardware/Accelerometer.cpp

@@ -10,7 +10,9 @@
 using namespace glass;
 
 void glass::DisplayAccelerometerDevice(AccelerometerModel* model) {
-  if (!model->Exists()) return;
+  if (!model->Exists()) {
+    return;
+  }
   if (BeginDevice("BuiltInAccel")) {
     // Range
     {