Add main thread work execution to app loop

Invoke WorkService::executeMainThreadWork and delegate's applicationMainLoop in the main application loop. This allows services and the app delegate to perform main-thread-specific tasks during each iteration.

Author: Geenz

src/Core/EntropyApplication.cpp

@@ -118,6 +118,12 @@ int EntropyApplication::run() {
                     // Continue waiting afterwards
                     continue;
                 }
+                
+                // Run the main thread work service jobs.
+                _services.get<Concurrency::WorkService>()->executeMainThreadWork();
+
+                // Let the app delegate execute its main thread work.
+                if (_delegate) _delegate->applicationMainLoop();
             }
         }
     }
@@ -145,6 +151,12 @@ int EntropyApplication::run() {
                     int signum = _lastSignal.load(std::memory_order_relaxed);
                     handlePosixSignal(signum);
                 }
+
+                // Run the main thread work service jobs.
+                _services.get<Concurrency::WorkService>()->executeMainThreadWork();
+
+                // Let the app delegate execute its main thread work.
+                if (_delegate) _delegate->applicationMainLoop();
             }
         } else {
             // Fallback to condition_variable if signal handlers not installed

src/Core/EntropyApplication.h

@@ -34,6 +34,7 @@ class EntropyAppDelegate {
     virtual bool applicationShouldTerminate() { return true; }
     virtual void applicationWillTerminate() {}
     virtual void applicationDidCatchUnhandledException(std::exception_ptr) {}
+    virtual void applicationMainLoop() {}
 };
 
 struct EntropyApplicationConfig {