Set sourceSize in for images, improving memory usage and smoothing

In some cases (where we don't get a thumbnail) we load the entire image,
which might be large. Even when we get a thumbnail, the smoothing we
apply doesn't get the best results and the only other option is
mipmapping which is more memory intensive - it stores progressively
smaller images but keeps all of them in memory.

Now the ImageDelegate sets the sourceSize, which helps reduce the memory
footprint (since Qt will throw away whatever parts of the image we don't
need) and makes the images look smoother when scaled. However,
AnimatedImages do not support this so this change introduces a new
property to tell if the image could possibly be animated. It will
erroneously pick up formats that could support animation (e.g. WebP) but
other image formats will still benefit so it's a net positive. The
ImageDelegate will load the correct image component depending on this
property.

src/models/messageeventmodel.cpp

@@ -20,6 +20,7 @@
 
 #include <QDebug>
 #include <QGuiApplication>
+#include <QMovie>
 #include <QTimeZone>
 
 #include <KLocalizedString>
@@ -969,6 +970,9 @@ QVariantMap MessageEventModel::getMediaInfoFromFileInfo(const EventContent::File
             mediaInfo["width"] = castInfo->imageSize.width();
             mediaInfo["height"] = castInfo->imageSize.height();
 
+            // TODO: Images in certain formats (e.g. WebP) will be erroneously marked as animated, even if they are static.
+            mediaInfo["animated"] = QMovie::supportedFormats().contains(mimeType.preferredSuffix().toUtf8());
+
             if (!isThumbnail) {
                 QVariantMap tempInfo;
                 auto thumbnailInfo = getMediaInfoFromFileInfo(castInfo->thumbnailInfo(), eventId, true);