Revert "chatview: remove useless /"

rfc1738 3.10 describes the file URL form: file://<host>/<path>
According to wikipedia, "file://path (i.e. two slashes, without a
hostname) is never correct, but is often used."

This reverts commit 4e6336d8.

Change-Id: Ic3f7c48eb5faa1ec97347328a03c8fda94513faf

src/commoncomponents/DataTransferMessageDelegate.qml

@@ -81,7 +81,7 @@ Loader {
                         enabled: canOpen
                         onHoveredChanged: {
                             dataTransferItem.hoveredLink = enabled && hovered ?
-                                        ("file://" + Body) : ""
+                                        ("file:///" + Body) : ""
                         }
                         cursorShape: enabled ?
                                          Qt.PointingHandCursor :
@@ -306,7 +306,7 @@ Loader {
                             antialiasing: true
                             autoTransform: false
                             asynchronous: true
-                            source: "file://" + Body
+                            source: "file:///" + Body
                             property real aspectRatio: implicitWidth / implicitHeight
                             property real adjustedWidth: Math.min(maxSize,
                                                                   Math.max(minSize,