[Dialogs] Add QueryDialog

src/controls/qml/QueryDialog.qml

+import QtQuick 2.6
+
+Item {
+    id: shell
+    anchors.fill: parent
+    signal accepted()
+    signal canceled()
+    property alias cancelText: cancel.text
+    property alias acceptText: accept.text
+    property alias headingText: heading.text
+    property alias subLabelText: subLabel.text
+
+
+    Rectangle {
+        anchors.fill: parent
+        opacity: 0.65
+        color: Theme.backgroundColor
+
+    }
+    Label {
+        width: parent.width*0.8
+        id: heading
+        anchors.centerIn: parent
+        horizontalAlignment: Text.AlignHCenter
+        font.weight: Theme.fontWeightLarge
+        wrapMode: Text.Wrap
+    }
+    Label {
+         id:subLabel
+         width: parent.width*0.8
+         wrapMode: Text.Wrap
+         font.weight: Theme.fontWeightMedium
+         horizontalAlignment: Text.AlignHCenter
+         anchors {
+             top:heading.bottom
+             topMargin: Theme.itemSpacingLarge
+             horizontalCenter: shell.horizontalCenter
+         }
+    }
+
+    Button {
+        id: cancel
+        width: parent.width / 2
+        height: Theme.itemHeightLarge
+        anchors {
+            left: parent.left
+            bottom: parent.bottom
+        }
+        onClicked: {
+            shell.canceled()
+            shell.destroy()
+        }
+    }
+    Button {
+        id: accept
+        width: parent.width / 2
+        height: Theme.itemHeightLarge
+        primary: true
+        anchors {
+            left: cancel.right
+            bottom: parent.bottom
+        }
+        onClicked: {
+            shell.accepted()
+            shell.destroy()
+        }
+    }
+}