Fix QML warnings regarding binding loops (#1829)

In aboutDialog (line 178), the binding loop was created because the height of aboutDialog wasn't set. It was dependent on the height of its child (aboutMessage). But aboutMessage had anchor.fill : parent set which binds its height to the height of its parent.

Similar reasoning applies to fileSaveFailure.

Signed-off-by: Addisu Z. Taddese <addisu@openrobotics.org>

src/gui/resources/GazeboDrawer.qml

@@ -183,6 +183,7 @@ Rectangle {
     focus: true
     parent: ApplicationWindow.overlay
     width: parent.width / 3 > 500 ? 500 : parent.width / 3
+    height: 300
     x: (parent.width - width) / 2
     y: (parent.height - height) / 2
     closePolicy: Popup.CloseOnEscape
@@ -292,6 +293,7 @@ Rectangle {
     modal: true
     focus: true
     parent: ApplicationWindow.overlay
+    width: messageText.implicitWidth
     x: (parent.width - width) / 2
     y: (parent.height - height) / 2
     closePolicy: Popup.CloseOnEscape