Everywhere: Use MonotonicTime instead of Duration

This is easily identifiable by anyone who uses Duration::now_monotonic,
and any downstream users of that data.

Userland/Libraries/LibWeb/HighResolutionTime/TimeOrigin.cpp

@@ -55,7 +55,7 @@ DOMHighResTimeStamp coarsened_shared_current_time(bool cross_origin_isolated_cap
 DOMHighResTimeStamp unsafe_shared_current_time()
 {
     // The unsafe shared current time must return the current value of the shared monotonic clock.
-    return Duration::now_monotonic().to_nanoseconds() / 1e6;
+    return MonotonicTime::now().truncated_seconds();
 }
 
 }