fix: Frame rate getting unlocked when inputs are being processed (#1632)

### Problem description
The framerate limiter doesn't work when inputs are being sent (eg mouse
cursor moving over the window), because `glfwWaitEventsTimeout` returns
early when it encounters an event.

### Implementation description
I made it sleep for the remaining time when that happens.

Author: onsatoci

main/gui/source/window/window.cpp

@@ -262,6 +262,13 @@ namespace hex {
                     const auto targetFrameTime = 1.0 / targetFPS;
                     if (frameTime < targetFrameTime) {
                         glfwWaitEventsTimeout(targetFrameTime - frameTime);
+
+                        // glfwWaitEventsTimeout might return early if there's an event
+                        const auto frameTime = glfwGetTime() - m_lastStartFrameTime;
+                        if (frameTime < targetFrameTime) {
+                            const auto timeToSleepMs = (int)((targetFrameTime - frameTime) * 1000);
+                            std::this_thread::sleep_for(std::chrono::milliseconds(timeToSleepMs));
+                        }
                     }
                 }
             }