Add break for default cases

Visual Studio has an option to search all files in a solution, so I
did a search in there for "default:" looking for any missing break
statements.

I've left out default statements that return something, and that throw
something, even if via ThrowInvalidType. UNREACHABLE leads towards throw

R_THROW macro leads towards a return

src/core/hle/service/time/time_zone_manager.cpp

@@ -280,6 +280,7 @@ static constexpr int TransitionTime(int year, Rule rule, int offset) {
     }
     default:
         ASSERT(false);
+        break;
     }
     return value + rule.transition_time + offset;
 }