Check lockscreen status for fullscreen effects

Whilst global shortcuts are blocked by grabbing the keyboard, user set
up manual scripts can still invoke a global action.

Given we already have code to deactivate when locking it makes sense to
also prevent activation.

BUG: 450331

src/effects/desktopgrid/desktopgrid.cpp

@@ -68,6 +68,9 @@ DesktopGridEffect::DesktopGridEffect()
 
     connect(a, &QAction::triggered, this, [this]() {
         if ((qreal(timeline.currentTime()) / qreal(timeline.duration())) > 0.5) {
+            if (effects->isScreenLocked()) {
+                return;
+            }
             activated = true;
             timeline.setDirection(QTimeLine::Forward);
             timelineRunning = true;

src/effects/overview/overvieweffect.cpp

@@ -155,6 +155,9 @@ void OverviewEffect::toggle()
 
 void OverviewEffect::activate()
 {
+    if (effects->isScreenLocked()) {
+        return;
+    }
     setRunning(true);
 }
 

src/effects/presentwindows/presentwindows.cpp

@@ -1592,6 +1592,9 @@ void PresentWindowsEffect::setActive(bool active)
         return;
     if (m_activated == active)
         return;
+    if (effects->isScreenLocked() && active) {
+        return;
+    }
 
     m_activated = active;
     if (m_activated) {