messageDialog: move yes to the right, no to the left.

According to the Google Android guidelines, "The dismissive action
of a dialog is always on the left."
source:
https://uxplanet.org/primary-secondary-action-buttons-c16df9b36150

electrum/gui/qml/components/MessageDialog.qml

@@ -54,19 +54,19 @@ ElDialog {
                 Layout.fillWidth: true
                 Layout.preferredWidth: 1
                 textUnderIcon: false
-                text: qsTr('Yes')
-                icon.source: Qt.resolvedUrl('../../icons/confirmed.png')
+                text: qsTr('No')
+                icon.source: Qt.resolvedUrl('../../icons/closebutton.png')
                 visible: yesno
-                onClicked: doAccept()
+                onClicked: doReject()
             }
             FlatButton {
                 Layout.fillWidth: true
                 Layout.preferredWidth: 1
                 textUnderIcon: false
-                text: qsTr('No')
-                icon.source: Qt.resolvedUrl('../../icons/closebutton.png')
+                text: qsTr('Yes')
+                icon.source: Qt.resolvedUrl('../../icons/confirmed.png')
                 visible: yesno
-                onClicked: doReject()
+                onClicked: doAccept()
             }
         }
     }