LinkPreviewComponent: Fix a few bugs, restore the image preview

We realized that images don't display in link previews anymore, because
QML is terrible and this property is a QUrl, so when we call .length it
silently fails and never loads the image. This is easily fixed by
calling .toString().

There's also another bug where the title ie elided way too greedily, but
we can simplify the elision check and fix the bug at the same time.
No more "Hom..."!

src/timeline/LinkPreviewComponent.qml

@@ -31,7 +31,7 @@ QQC2.Control {
      *  - description - the description of the URL preview.
      *  - imageSource - a source URL for the preview image.
      */
-    required property var linkPreviewer
+    required property LinkPreviewer linkPreviewer
 
     /**
      * @brief Standard height for the link preview.
@@ -72,7 +72,9 @@ QQC2.Control {
             id: previewImage
             Layout.preferredWidth: root.defaultHeight
             Layout.preferredHeight: root.defaultHeight
-            visible: root.linkPreviewer.imageSource.length > 0
+            Layout.fillWidth: true
+            Layout.fillHeight: true
+            visible: root.linkPreviewer.imageSource.toString().length > 0
             source: root.linkPreviewer.imageSource
             fillMode: Image.PreserveAspectFit
         }
@@ -80,6 +82,7 @@ QQC2.Control {
             id: column
             implicitWidth: Math.max(linkPreviewTitle.implicitWidth, linkPreviewDescription.implicitWidth)
             spacing: Kirigami.Units.smallSpacing
+            visible: root.linkPreviewer.title.length > 0 || root.linkPreviewer.description.length > 0
             Kirigami.Heading {
                 id: linkPreviewTitle
                 Layout.fillWidth: true
@@ -98,12 +101,7 @@ QQC2.Control {
                     text: root.linkPreviewer.title
                     font: linkPreviewTitle.font
                     elide: Text.ElideRight
-                    elideWidth: (linkPreviewTitle.availableWidth()) * 3
-                }
-
-                function availableWidth() {
-                    let previewImageWidth = (previewImage.visible ? previewImage.width + contentRow.spacing : 0);
-                    return root.maxContentWidth - contentRow.spacing - separator.width - previewImageWidth;
+                    elideWidth: linkPreviewTitle.width
                 }
             }
             QQC2.Label {