Rework fullscreen image

As discussed in network/neochat#161, when clicking the image it now only covers the neochat window. A modal popup that covers the neochat window is now used. The app behind get dimmed.

Left clicking anywhere closes the preview as well as the using the close button. Right clicking on the image itself still gives the image's context menu.

Before
![fullscreenimage_before](/uploads/f7a64ab2f0b75405f3f0a16f32c029f3/fullscreenimage_before.png)

After
![fullscreenimage_updated2](/uploads/8feb6c79891019203a6a0a8439c71b70/fullscreenimage_updated2.png)

Latest
![fullscreenimage_updated_final](/uploads/61ca4c1251b914ae3a6bdd158f4dc396/fullscreenimage_updated_final.png)

Closes network/neochat#161

imports/NeoChat/Component/Timeline/ImageDelegate.qml

@@ -6,6 +6,8 @@ import QtQuick.Controls 2.15
 import QtQuick.Layouts 1.15
 import Qt.labs.platform 1.1
 
+import org.kde.kirigami 2.15 as Kirigami
+
 import org.kde.neochat 1.0
 import NeoChat.Component 1.0
 import NeoChat.Dialog 1.0
@@ -50,6 +52,7 @@ TimelineContainer {
 
         ToolTip.text: model.display
         ToolTip.visible: hoverHandler.hovered
+        ToolTip.delay: Kirigami.Units.toolTipDelay
 
         HoverHandler {
             id: hoverHandler
@@ -89,17 +92,21 @@ TimelineContainer {
             acceptedButtons: Qt.LeftButton
             onLongPressed: openFileContext(model, parent)
             onTapped: {
-                fullScreenImage.createObject(parent, {
-                    filename: eventId,
-                    source: mediaUrl,
-                    blurhash: model.content.info["xyz.amorgan.blurhash"],
-                    imageWidth: content.info.w,
-                    imageHeight: content.info.h,
-                    modelData: model
-                }).showFullScreen();
+                img.ToolTip.hide()
+                fullScreenImage.open()
             }
         }
 
+        FullScreenImage {
+            id: fullScreenImage
+            filename: eventId
+            source: mediaUrl
+            blurhash: model.content.info["xyz.amorgan.blurhash"]
+            imageWidth: content.info.w
+            imageHeight: content.info.h
+            modelData: model
+        }
+
         function downloadAndOpen() {
             if (downloaded) {
                 openSavedFile()