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).

wpiutil/src/test/native/cpp/sigslot/signal.cpp

@@ -45,8 +45,12 @@ namespace {
 
 int sum = 0;
 
-void f1(int i) { sum += i; }
-void f2(int i) /*noexcept*/ { sum += 2 * i; }
+void f1(int i) {
+  sum += i;
+}
+void f2(int i) /*noexcept*/ {
+  sum += 2 * i;
+}
 
 struct s {
   static void s1(int i) { sum += i; }