[Companion] Qualify all translation strings (#5557)

* [Companion] Qualify all remaining QObject translations with proper class/object names; Centralize some common strings into constants.h.

* [Companion] Replace all instances of some common strings with macros from constants.h.

* [Companion] Fix translation warnings from lupdate.

companion/src/simulation/simulatorwidget.cpp

@@ -649,7 +649,7 @@ void SimulatorWidget::setupJoysticks()
       joysticksEnabled = true;
     }
     else {
-      QMessageBox::critical(this, tr("Warning"), tr("Cannot open joystick, joystick disabled"));
+      QMessageBox::critical(this, CPN_STR_TTL_WARNING, tr("Cannot open joystick, joystick disabled"));
     }
   }
   else if (joystick) {