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).

wpilibNewCommands/src/test/native/cpp/frc2/command/ErrorConfirmer.h

@@ -11,7 +11,9 @@
 class ErrorConfirmer {
  public:
   explicit ErrorConfirmer(const char* msg) : m_msg(msg) {
-    if (instance != nullptr) return;
+    if (instance != nullptr) {
+      return;
+    }
     HALSIM_SetSendError(HandleError);
     EXPECT_CALL(*this, ConfirmError());
     instance = this;