Added tab navigation functional. (#721)

- Added tab navigation functional.
- In basic types added parentFlickable property, which will help to ensure, that the item is visible within flickable parent during tab navigation.
- Added focus state for some basic types.
- In PageType qml file added lastItemTabClicked function, which will help to focus tab bar buttons when the last tab on the current page clicked.
- Added Focus for back button for all pages and drawers.
- Added scroll on tab for Servers ListView on PageHome.

client/ui/qml/Pages2/PageSettingsAppSplitTunneling.qml

@@ -20,6 +20,8 @@ import "../Components"
 PageType {
     id: root
 
+    defaultActiveFocusItem: focusItem
+
     property bool pageEnabled
 
     Component.onCompleted: {
@@ -63,6 +65,11 @@ PageType {
         }
     }
 
+    Item {
+        id: focusItem
+        KeyNavigation.tab: backButton
+    }
+
     ColumnLayout {
         id: header
 
@@ -73,6 +80,8 @@ PageType {
         anchors.topMargin: 20
 
         BackButtonType {
+            id: backButton
+            KeyNavigation.tab: switcher
         }
 
         RowLayout {
@@ -93,6 +102,10 @@ PageType {
 
                 enabled: root.pageEnabled
 
+                KeyNavigation.tab: selector.enabled ?
+                                       selector :
+                                       searchField.textField
+
                 checked: AppSplitTunnelingModel.isTunnelingEnabled
                 onToggled: {                    
                     AppSplitTunnelingModel.toggleSplitTunneling(checked)
@@ -116,6 +129,8 @@ PageType {
 
             enabled: Qt.platform.os === "android" && root.pageEnabled
 
+            KeyNavigation.tab: searchField.textField
+
             listView: ListViewWithRadioButtonType {
                 rootWidth: root.width
 
@@ -251,6 +266,9 @@ PageType {
             textFieldPlaceholderText: qsTr("application name")
             buttonImageSource: "qrc:/images/controls/plus.svg"
 
+            Keys.onTabPressed: lastItemTabClicked(focusItem)
+            rightButtonClickedOnEnter: true
+
             clickedFunc: function() {
                 searchField.focus = false
                 PageController.showBusyIndicator(true)