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/PageSetupWizardConfigSource.qml

@@ -22,6 +22,8 @@ PageType {
         }
     }
 
+    defaultActiveFocusItem: focusItem
+
     FlickableType {
         id: fl
         anchors.top: parent.top
@@ -37,8 +39,15 @@ PageType {
 
             spacing: 0
 
+            Item {
+                id: focusItem
+                KeyNavigation.tab: backButton
+            }
+
             BackButtonType {
+                id: backButton
                 Layout.topMargin: 20
+                KeyNavigation.tab: fileButton.rightButton
             }
 
             HeaderType {
@@ -61,6 +70,7 @@ PageType {
             }
 
             LabelWithButtonType {
+                id: fileButton
                 Layout.fillWidth: true
                 Layout.topMargin: 16
 
@@ -68,6 +78,8 @@ PageType {
                 rightImageSource: "qrc:/images/controls/chevron-right.svg"
                 leftImageSource: "qrc:/images/controls/folder-open.svg"
 
+                KeyNavigation.tab: qrButton.visible ? qrButton.rightButton : textButton.rightButton
+
                 clickedFunction: function() {
                     var nameFilter = !ServersModel.getServersCount() ? "Config or backup files (*.vpn *.ovpn *.conf *.json *.backup)" :
                                                                        "Config files (*.vpn *.ovpn *.conf *.json)"
@@ -83,6 +95,7 @@ PageType {
             DividerType {}
 
             LabelWithButtonType {
+                id: qrButton
                 Layout.fillWidth: true
                 visible: SettingsController.isCameraPresent()
 
@@ -90,6 +103,8 @@ PageType {
                 rightImageSource: "qrc:/images/controls/chevron-right.svg"
                 leftImageSource: "qrc:/images/controls/qr-code.svg"
 
+                KeyNavigation.tab: textButton.rightButton
+
                 clickedFunction: function() {
                     ImportController.startDecodingQr()
                     if (Qt.platform.os === "ios") {
@@ -103,12 +118,15 @@ PageType {
             }
 
             LabelWithButtonType {
+                id: textButton
                 Layout.fillWidth: true
 
                 text: qsTr("Key as text")
                 rightImageSource: "qrc:/images/controls/chevron-right.svg"
                 leftImageSource: "qrc:/images/controls/text-cursor.svg"
 
+                Keys.onTabPressed: lastItemTabClicked(focusItem)
+
                 clickedFunction: function() {
                     PageController.goToPage(PageEnum.PageSetupWizardTextKey)
                 }