Add new dashboard item to show elapsed times (closes #2234). Cleanup handling of TimeConversion and add unit testing

include/openspace/util/timeconversion.h

@@ -168,7 +168,10 @@ constexpr TimeUnit timeUnitFromString(std::string_view unitName) {
     }
 }
 
-std::pair<double, std::string> simplifyTime(double seconds,
+std::pair<double, std::string_view> simplifyTime(double seconds,
+    bool forceSingularForm = false);
+
+std::vector<std::pair<double, std::string_view>> splitTime(double seconds,
     bool forceSingularForm = false);
 
 constexpr double convertTime(double t, TimeUnit sourceUnit, TimeUnit destinationUnit) {