Monitor Tab - Use camera button on camera stream

- Fixes: Video feed close button is always out of sight
- Makes improvement to camera icon

Contributes to CL-1049

plugins/UM3NetworkPrinting/resources/qml/CameraButton.qml

@@ -0,0 +1,47 @@
+import QtQuick 2.3
+import QtQuick.Controls 1.4
+import QtQuick.Controls.Styles 1.3
+import QtQuick.Controls 2.0 as Controls2
+import QtGraphicalEffects 1.0
+
+import UM 1.3 as UM
+import Cura 1.0 as Cura
+
+Rectangle
+{
+    property var iconSource: null
+
+    width: 36 * screenScaleFactor
+    height: width
+    radius: 0.5 * width
+    color: clickArea.containsMouse ? UM.Theme.getColor("primary_hover") : UM.Theme.getColor("primary")
+
+    UM.RecolorImage
+    {
+        id: icon
+        width: parent.width / 2
+        height: width
+        anchors.verticalCenter: parent.verticalCenter
+        anchors.horizontalCenter: parent.horizontalCenter
+        color: UM.Theme.getColor("primary_text")
+        source: iconSource
+    }
+
+    MouseArea
+    {
+        id: clickArea
+        anchors.fill:parent
+        hoverEnabled: true
+        onClicked:
+        {
+            if (OutputDevice.activeCamera !== null)
+            {
+                OutputDevice.setActiveCamera(null)
+            }
+            else
+            {
+                OutputDevice.setActiveCamera(modelData.camera)
+            }
+        }
+    }
+}